WEBVTT - TechStuff Classic: How the Industrial Revolution Worked, Part Two 0:00:04.400 --> 0:00:07.800 Welcome to tech Stuff, a production from my Heart Radio. 0:00:11.840 --> 0:00:14.000 Hey there, and welcome to tech Stuff. I'm your host, 0:00:14.120 --> 0:00:16.880 Jonathan Strickland. I'm an executive producer with iHeart Radio and 0:00:16.920 --> 0:00:20.280 how the tech are you. It's time for a classic episode, 0:00:20.280 --> 0:00:23.040 and we're going to continue where we left off last 0:00:23.079 --> 0:00:27.440 week in last week's classic episode about the Industrial Revolution. 0:00:27.600 --> 0:00:31.560 This is part two of three. This episode originally published 0:00:31.560 --> 0:00:36.720 on November two thousand and fifteen. Fortunately, unlike a lot 0:00:36.760 --> 0:00:39.480 of my topics I cover on tech Stuff, the Industrial 0:00:39.560 --> 0:00:42.960 Revolution has not changed significantly in the last seven years. 0:00:43.200 --> 0:00:47.199 So let's sit back and listen. Now. In that last episode, 0:00:48.040 --> 0:00:51.559 I focused mainly on the textile industry because it's a 0:00:51.560 --> 0:00:55.000 great illustration of how quickly things changed just within a 0:00:55.000 --> 0:00:57.840 few decades and went from something that used to be 0:00:57.880 --> 0:01:01.600 a specialized skill among we vers that would do you know, 0:01:01.640 --> 0:01:05.480 maybe a couple would work together, but that would be it, 0:01:05.720 --> 0:01:07.520 and it would be something that would be produced on 0:01:07.560 --> 0:01:11.000 a very small scale, to a full blown industry which 0:01:11.000 --> 0:01:15.119 would end up employing thousands of people. Now, in this 0:01:15.200 --> 0:01:18.679 week's episode, we're gonna look more closely at how iron 0:01:19.000 --> 0:01:22.920 shaped the Industrial Revolution and how innovations and inventions in 0:01:22.959 --> 0:01:27.840 the iron industry really changed things, and it's it's fascinating 0:01:27.959 --> 0:01:31.800 and also kind of complicated. Now, first of all, iron 0:01:31.920 --> 0:01:36.000 is the second most common metal in the Earth's crust. 0:01:36.440 --> 0:01:40.280 The most common would be aluminum. But we would never 0:01:40.319 --> 0:01:44.240 really use chemically pure iron, you know, the fe stuff 0:01:44.680 --> 0:01:49.200 to build anything of any significance. And that's because of 0:01:49.280 --> 0:01:51.919 a couple of things. See, pure iron is really malleable, 0:01:52.120 --> 0:01:53.920 so that it means it's really easy to shape, so 0:01:53.960 --> 0:01:58.960 that's good. And you can even cut pure iron using 0:01:59.000 --> 0:02:02.040 something like a knife. If you've got a hunk of 0:02:02.320 --> 0:02:05.280 chemically pure iron, you can cut through it. It does 0:02:05.360 --> 0:02:07.560 take some effort, it's not like it's gonna slice through 0:02:07.600 --> 0:02:10.760 like butta, but you can do it. You can use 0:02:10.760 --> 0:02:14.120 a hammer to beat pure iron into sheets, or you 0:02:14.160 --> 0:02:17.880 can even draw it into wires. And it's great stuff. 0:02:17.880 --> 0:02:21.280 I mean, it conducts heat, it conducts electricity. It's also 0:02:21.400 --> 0:02:24.239 really easy to magnetize, so it's got a lot of uses. 0:02:25.200 --> 0:02:28.920 But it isn't strong or hard enough in order to 0:02:29.000 --> 0:02:33.440 use for building structures like bridges or buildings or canals 0:02:33.600 --> 0:02:37.679 or or even common tools. It's not strong enough to 0:02:37.680 --> 0:02:40.280 to do that. It will end up bending too too much. 0:02:40.680 --> 0:02:43.480 So all of that is kind of a moot point 0:02:44.280 --> 0:02:47.519 because there's something else about iron that gives it a 0:02:47.600 --> 0:02:51.919 huge drawback. We don't see much pure iron because it's 0:02:51.919 --> 0:02:56.760 got a habit of getting really familiar with oxygen. Oxygen 0:02:56.840 --> 0:03:01.000 corrodes iron, particularly in moist conditions, so that causes a 0:03:01.080 --> 0:03:05.639 chemical reaction in which pure iron forms an iron oxide 0:03:05.639 --> 0:03:09.560 that we call rust. So that's essentially what's happening, is 0:03:09.600 --> 0:03:13.639 this chemical reaction with iron and oxygen creates this iron 0:03:13.639 --> 0:03:17.440 oxide of rust that we don't really want. You know, 0:03:17.480 --> 0:03:19.640 there's always about you know, you have to scrub down 0:03:19.720 --> 0:03:21.320 the rust and get rid of it, or else it 0:03:21.400 --> 0:03:25.520 just continues to corrode. Well, because iron reacts so readily 0:03:25.560 --> 0:03:28.679 to oxygen, we don't mind iron in its pure form. 0:03:28.720 --> 0:03:30.760 In fact, we just we don't find it because it 0:03:30.800 --> 0:03:34.840 oxidizes so quickly. Instead, we mine iron oxides that are 0:03:34.880 --> 0:03:39.200 locked inside various types of ore, including hematite, which is 0:03:39.280 --> 0:03:44.119 the most plentiful ore that contains iron, limonite or limonite, 0:03:44.160 --> 0:03:46.200 depending on how you want to pronounce it, sometimes called 0:03:46.280 --> 0:03:50.560 bog iron, and magnetite, which is also known as loadstone, 0:03:50.640 --> 0:03:53.360 among others. There are a few other versions of iron 0:03:53.360 --> 0:03:56.760 ore as well. Not all ores contain the same percentage 0:03:56.760 --> 0:03:59.880 of iron by volume, and we mine iron both in 0:04:00.120 --> 0:04:03.600 underground mines and in surface mining. It all depends upon 0:04:03.680 --> 0:04:07.800 where you are and where the iron deposits happened to be. Now, 0:04:07.800 --> 0:04:11.480 the iron ore in Britain, because that again is where 0:04:11.480 --> 0:04:16.160 the Industrial Revolution began, had really high concentrations of sulfur 0:04:16.240 --> 0:04:20.279 and phosphorus, and both of those things will make iron 0:04:20.320 --> 0:04:23.520 brittle if you don't get rid of them. So until 0:04:23.520 --> 0:04:27.360 the Industrial Revolution, iron masters hadn't really quite worked out 0:04:27.520 --> 0:04:31.599 how to do that on an efficient basis. For that reason, 0:04:31.640 --> 0:04:36.800 British iron was often used in very cheap items like nails. Now, 0:04:37.160 --> 0:04:40.640 this was also a little tricky because iron making iron 0:04:40.680 --> 0:04:43.839 required a lot of labor, a lot of backbreaking hard work, 0:04:44.240 --> 0:04:47.280 and that drove up the price of the final product. 0:04:47.800 --> 0:04:52.400 So Britain was starting to supplement its own iron supplies 0:04:52.440 --> 0:04:55.040 by importing about half of all the iron it was 0:04:55.160 --> 0:04:58.560 using from Sweden. The iron from Sweden did not have 0:04:59.080 --> 0:05:02.440 the high concentrateations of sulfur or phosphorus, so it wasn't 0:05:02.520 --> 0:05:06.080 as problematic, and Britain just couldn't produce enough of its 0:05:06.080 --> 0:05:10.240 own despite ample supplies of iron ore. Now, once we 0:05:10.279 --> 0:05:13.320 get hold of iron ore, we have to smelt it. 0:05:14.360 --> 0:05:16.200 That's in order for us to get to the iron 0:05:16.200 --> 0:05:19.120 that's inside of it. Now, this involves heating the ore 0:05:19.320 --> 0:05:23.040 up to the melting point of iron. We also use 0:05:23.200 --> 0:05:26.280 fuels that will produce chemicals that can bond with the 0:05:26.320 --> 0:05:32.120 iron during this process, which changes iron's physical characteristics. We're 0:05:32.120 --> 0:05:35.719 talking chemical reactions here, and what we're really doing is 0:05:35.760 --> 0:05:40.039 creating iron alloys. And an alloy is a mixture that 0:05:40.120 --> 0:05:43.080 has a metal with something else. Sometimes it's another metal, 0:05:43.200 --> 0:05:46.640 sometimes it's a different substance. But these are chemical mixtures 0:05:46.640 --> 0:05:51.560 that have their own features that are different from the 0:05:51.680 --> 0:05:57.320 features of the individual elements or or ingredients in that mixture, 0:05:57.640 --> 0:06:01.880 so you're getting something new. The main ingredient we mix 0:06:01.960 --> 0:06:06.000 with iron to produce useful material is carbon, and if 0:06:06.000 --> 0:06:08.479 you get the mix of carbon to iron just right, 0:06:08.520 --> 0:06:12.719 you produce steel. Steel is an iron alloy that has 0:06:12.760 --> 0:06:16.760 around two or less carbon in it. Other types of 0:06:16.800 --> 0:06:20.200 iron hab between two to four of carbon in the alloy, 0:06:20.279 --> 0:06:23.279 and mixing other metals or substances will create different types 0:06:23.360 --> 0:06:28.240 of steel or iron. So how do you mix carbon 0:06:28.600 --> 0:06:32.279 into the iron? What exactly are you doing here is 0:06:32.320 --> 0:06:35.719 there's some sort of powder that you're pouring in. Well, 0:06:35.760 --> 0:06:40.080 one way is by using a carbon rich fuel as 0:06:40.160 --> 0:06:42.560 the means of heating up your iron to melt it 0:06:43.000 --> 0:06:44.880 in the first place. So if you're using something a 0:06:44.920 --> 0:06:47.640 fuel that has a lot of carbon in it, then 0:06:47.760 --> 0:06:50.440 some of that carbon gets transferred into the iron as 0:06:50.480 --> 0:06:55.800 it melts. Charcoal is a great example, and iron masters 0:06:56.040 --> 0:07:00.400 in Britain and really all over Europe relied very heavily 0:07:00.440 --> 0:07:05.000 on charcoal for centuries when smelting iron ore. But if 0:07:05.000 --> 0:07:07.440 you remember from our last episode, I talked about a 0:07:07.480 --> 0:07:11.240 man named Abraham Darby who came up with an alternative 0:07:11.320 --> 0:07:16.280 to charcoal, and it was coke. Now, coke is a 0:07:16.320 --> 0:07:20.280 fuel product you make by baking coal in an airless 0:07:20.320 --> 0:07:24.560 oven or furnace at a really high temperature, and at 0:07:24.600 --> 0:07:27.440 that high temperature, some of the coal begins to ash. 0:07:27.560 --> 0:07:32.160 That ash will end up melding with the the coal 0:07:32.240 --> 0:07:35.559 itself and it converts into this other fuel called coke, 0:07:36.440 --> 0:07:39.880 which is once it cools down, grayish in color and 0:07:39.920 --> 0:07:43.680 has a very porous structure. When you burn coke, it 0:07:43.760 --> 0:07:47.400 creates carbon monoxide, among other things, which is important in 0:07:47.440 --> 0:07:52.400 this process of creating iron useful iron. But why would 0:07:52.440 --> 0:07:55.360 anyone worry about switching from charcoal to coke in the 0:07:55.360 --> 0:07:57.720 first place. I mean, charcoal is pretty simple. You just 0:07:57.800 --> 0:08:01.680 have to burn wood to make charcoal. Uh. And in fact, 0:08:02.520 --> 0:08:04.720 this is where the problem would come in. In order 0:08:04.840 --> 0:08:10.760 to fuel a single iron works for one year, it 0:08:10.800 --> 0:08:15.160 would take two acres of forest to supply enough charcoal 0:08:15.200 --> 0:08:19.440 for operations. So for one iron works, you would need 0:08:19.480 --> 0:08:22.840 two hundred acres of woods. And keep in mind that 0:08:23.040 --> 0:08:25.920 once you've gone through that that two acres of forests 0:08:26.000 --> 0:08:28.520 in a year, you're not gonna be able to use 0:08:28.560 --> 0:08:31.440 those same two hundred acres the next year because it's 0:08:31.440 --> 0:08:34.120 going to take time for that forest to grow back. 0:08:35.000 --> 0:08:39.160 So we saw a steady decrease in the forests of 0:08:39.240 --> 0:08:43.040 Britain during this time period. At this time, iron works 0:08:43.080 --> 0:08:46.720 were mostly located in forests because it was cheaper to 0:08:46.800 --> 0:08:50.160 ship the iron ore and iron from the iron works 0:08:50.280 --> 0:08:52.040 or to the iron works, and from the iron works 0:08:52.480 --> 0:08:56.600 then it was to ship charcoal around, so they located 0:08:56.640 --> 0:08:59.360 the iron works near the fuel, not the iron ore, 0:08:59.559 --> 0:09:04.720 which seems counterintuitive at first, but eventually the growth of 0:09:04.760 --> 0:09:08.640 the iron industry and the fact that more and more 0:09:09.679 --> 0:09:13.440 people were building ships during this time period for England 0:09:13.960 --> 0:09:16.080 meant that England was using up more wood than it 0:09:16.120 --> 0:09:20.959 could replenish, So charcoal became more expensive because forests were 0:09:20.960 --> 0:09:25.200 being chopped down, wood was becoming a scarce commodity comparatively 0:09:25.280 --> 0:09:28.160 speaking compared to how it had been in previous centuries, 0:09:28.679 --> 0:09:31.880 so it became really expensive to use forests just to 0:09:31.920 --> 0:09:36.080 generate charcoal. So an alternative fuel was definitely needed to 0:09:36.240 --> 0:09:41.800 make British iron and actual commodity. Now, some iron masters 0:09:41.840 --> 0:09:46.840 tried using coal as fuel, but burning coal produces sulfur, 0:09:47.080 --> 0:09:49.920 and that sulfur would react to the melted iron ore 0:09:49.960 --> 0:09:51.880 and produce an iron that was too brittle to be 0:09:51.960 --> 0:09:56.520 of much use. Coke, however, didn't produce nearly as much 0:09:56.559 --> 0:10:00.280 sulfur when burned, and the carbon monoxide coke produces wind 0:10:00.320 --> 0:10:02.480 burn would mix with the melted iron ore to create 0:10:02.640 --> 0:10:06.240 useful iron. And if you listen to that last episode, 0:10:06.880 --> 0:10:09.920 you heard that Abraham Darby had developed a process for 0:10:10.040 --> 0:10:13.120 making pig iron by using coke as the fuel while 0:10:13.240 --> 0:10:17.120 smelting iron ore, but his approach wasn't adopted by the 0:10:17.160 --> 0:10:20.880 iron industry during his lifetime. There are a couple of 0:10:20.920 --> 0:10:24.160 reasons for that that, you know, the iron industry didn't 0:10:24.200 --> 0:10:28.080 immediately swap to using coke instead of charcoal. One of 0:10:28.120 --> 0:10:31.760 those reasons is that Darby pretty much kept his process 0:10:31.760 --> 0:10:36.160 a secret and only told his son, Abraham Darby the second, 0:10:36.679 --> 0:10:39.800 how to do it. At the time, anyone wanted to, 0:10:40.280 --> 0:10:42.520 you know, get an advantage over their competitors, what they 0:10:42.520 --> 0:10:45.320 did was they kept their methods secret. Some people would 0:10:45.360 --> 0:10:48.800 choose to patent ideas to protect them. Others decided that 0:10:48.840 --> 0:10:52.080 patents were bad because if you if you file a patent, 0:10:52.360 --> 0:10:55.400 the information on how you do something becomes public knowledge 0:10:55.960 --> 0:11:00.320 and eventually passes into the public domain. So other than 0:11:00.400 --> 0:11:03.199 patent of process, some people would try and keep it 0:11:03.280 --> 0:11:06.920 a secret. That's what Derby did. But the other reason 0:11:06.920 --> 0:11:09.760 is that Darby didn't live to a very ripe old age. 0:11:09.840 --> 0:11:13.600 He actually had a really long illness and died at 0:11:13.679 --> 0:11:19.520 age thirty eight in seventeen seventeen. Now, his grandson, Abraham 0:11:19.600 --> 0:11:22.960 Derby the third would build the first iron bridge in 0:11:23.000 --> 0:11:26.760 the late seventeen seventies. But the Derby's method was really 0:11:26.760 --> 0:11:29.760 only good for creating a particular type of iron called 0:11:30.000 --> 0:11:32.960 cast iron. And I'll talk more about what cast iron 0:11:33.040 --> 0:11:36.760 is in just a minute. But first, let's talk about 0:11:36.800 --> 0:11:40.120 the smelting process. All right. So let's say you've got 0:11:40.200 --> 0:11:43.560 yourself an iron furnace. Typically we would talk about a 0:11:43.600 --> 0:11:49.520 blast furnace. Blast furnaces are really giant cylinders. We're talking 0:11:49.720 --> 0:11:52.200 some of them being around thirty to forty ft tall 0:11:52.240 --> 0:11:56.160 and twenty to thirty ft square at the base, often 0:11:56.160 --> 0:12:00.320 built into the side of a hill. So that way, uh, 0:12:00.360 --> 0:12:04.720 in order to bring materials to the blast furnace, which 0:12:04.720 --> 0:12:08.120 you would deposit in the top of the furnace, you 0:12:08.160 --> 0:12:11.440 would climb the hill as opposed to putting scaffolding up 0:12:11.520 --> 0:12:13.640 or a long ramp or however you would you know, 0:12:13.840 --> 0:12:16.080 be able to have an access point to get to 0:12:16.120 --> 0:12:19.120 the top of the furnace. Now, if you want to 0:12:19.200 --> 0:12:21.760 imagine what these things look like, they did like a 0:12:21.960 --> 0:12:25.280 look like a tapering cylinder. So the top is a 0:12:25.280 --> 0:12:30.000 bit narrower than the bottom. Uh. The topmost portion of 0:12:30.040 --> 0:12:32.599 the cylinder is called the shaft, and that's where you 0:12:32.600 --> 0:12:35.760 would feed the fuel, the iron ore and some other 0:12:35.840 --> 0:12:40.600 materials called flux, which is typically limestone. The purpose of 0:12:40.640 --> 0:12:43.920 the flux is to absorb some of the other elements 0:12:44.000 --> 0:12:48.280 inside the iron ore that you don't want corrupting your iron. 0:12:48.360 --> 0:12:51.600 You don't want it to mix with the iron so 0:12:51.679 --> 0:12:54.559 that it makes it have properties that you weren't intending. 0:12:55.120 --> 0:12:59.160 So you've got your your flux, your fuel in this 0:12:59.200 --> 0:13:02.400 case coke or charcoal, and then the iron ore itself. 0:13:03.480 --> 0:13:05.840 You would put all that down the shaft. If you 0:13:05.920 --> 0:13:09.760 look down the cylinder, then the next section is called 0:13:10.000 --> 0:13:15.760 the bosch. This is a roughly circular chamber where uh 0:13:15.960 --> 0:13:19.800 it gets incredibly hot. And below the bosch, at the 0:13:19.840 --> 0:13:24.520 base of the blast furnace was the hearth or crucible, 0:13:24.559 --> 0:13:27.200 and that's where the molten iron would accumulate before being 0:13:27.280 --> 0:13:30.040 drawn off by the iron master. Drawn off just means 0:13:30.120 --> 0:13:36.920 essentially drained from the furnace chamber. So this was actually 0:13:37.000 --> 0:13:40.720 a pretty complicated process. Uh. In fact, they were called 0:13:40.720 --> 0:13:45.040 blast furnaces because you would blow large drafts of air 0:13:45.480 --> 0:13:49.400 into the furnace and what we're called blasts. The earliest 0:13:49.400 --> 0:13:53.280 blast furnaces were cold air furnaces, meaning that the the 0:13:53.400 --> 0:13:56.679 air being blown into the furnace had not been preheated 0:13:56.720 --> 0:13:59.520 in any way. The air would typically be forced through 0:13:59.520 --> 0:14:02.480 an entry point that's down the cylinder. It's not at 0:14:02.480 --> 0:14:07.040 the top, so you're not blowing air down into a chimney. Rather, 0:14:07.160 --> 0:14:10.760 you would have an entry point inside the furnace and 0:14:10.920 --> 0:14:13.760 air would come in there towards the bottom. You want 0:14:13.760 --> 0:14:17.760 it near the bottom to fan the flames, and that 0:14:17.800 --> 0:14:19.760 would allow you to keep the fire burning at the 0:14:19.880 --> 0:14:23.120 right temperature. And you would do this with an enormous 0:14:23.320 --> 0:14:28.200 set of bellows. So you've probably seen bellows. These are 0:14:28.280 --> 0:14:34.160 the devices made to actually blow air into a an area, 0:14:34.280 --> 0:14:38.520 usually some form of furnace or fire that would provide 0:14:38.560 --> 0:14:41.080 the blasts of air. And in the early Industrial Revolution 0:14:41.080 --> 0:14:43.760 they were powered by a water wheel. And when I 0:14:43.840 --> 0:14:46.240 say an enormous pair of bellows, I mean we're talking 0:14:46.760 --> 0:14:50.040 a big, big piece of machinery. They would be more 0:14:50.080 --> 0:14:53.280 than twenty ft long and four or five ft wide, 0:14:54.280 --> 0:14:59.000 So these were huge and would create very powerful blasts 0:14:59.080 --> 0:15:02.400 of air. Now, later iron masters would actually rely upon 0:15:02.520 --> 0:15:05.760 steam engines to power a blower for the furnace. But 0:15:05.800 --> 0:15:08.480 we'll talk more about steam engines towards the end of 0:15:08.520 --> 0:15:13.600 this episode. So if you wanted to start up in ironworks, 0:15:14.040 --> 0:15:16.520 you've just you've just decided to get into the business, 0:15:16.680 --> 0:15:20.720 and you're an eighteenth century England then what you would 0:15:20.720 --> 0:15:24.320 need to do is build your blast furnace in a 0:15:24.400 --> 0:15:28.360 in a good location, get all the stuff ready, like 0:15:28.400 --> 0:15:31.240 the bellows and everything all prepared, and then you would 0:15:31.240 --> 0:15:33.800 need to get your furnace up to the right temperature 0:15:34.200 --> 0:15:39.200 before you actually started to add iron ore. Uh. You 0:15:39.720 --> 0:15:42.920 would do this in a process that was called blowing in. 0:15:43.880 --> 0:15:46.280 Now that involved bringing a large amount of fuel into 0:15:46.360 --> 0:15:49.640 the furnace, whether it's charcoal or coke or whatever. You 0:15:49.640 --> 0:15:52.000 would have to ignite the fuel and allow it to 0:15:52.560 --> 0:15:56.720 gradually heat the furnace over about a week's worth of time, 0:15:57.640 --> 0:16:00.520 and once it was up to the proper temperature, you 0:16:00.520 --> 0:16:03.200 could finally get started with iron working. And when you're 0:16:03.200 --> 0:16:06.280 ready to smell iron, you feed the fuel, flux and 0:16:06.360 --> 0:16:09.080 iron ore into the top of the furnace. You're essentially 0:16:09.200 --> 0:16:14.280 dumping things down this this cylinder, this chimney. Now, as 0:16:14.280 --> 0:16:16.840 those materials fall through the length of the furnace, they 0:16:16.880 --> 0:16:19.120 begin to heat up. There's a lot of very hot 0:16:19.160 --> 0:16:22.960 gases that are rising up through this cylinder, and the 0:16:23.040 --> 0:16:26.360 material passes through those hot gases, getting hot before they 0:16:26.440 --> 0:16:31.280 even get toward the hearts the crucible. The fuel begins 0:16:31.320 --> 0:16:34.360 to burn and the iron starts to heat up to 0:16:34.480 --> 0:16:37.880 melting temperature. The iron ore reacts with the charcoal or 0:16:37.880 --> 0:16:41.080 the coke, and that absorbs the oxygen in the iron 0:16:41.080 --> 0:16:44.360 oxide that was locked away inside the iron ore. Now 0:16:44.400 --> 0:16:47.920 this is a process called reduction, and what you're left 0:16:47.960 --> 0:16:52.520 with is liquid iron and slag. Slag is actually not 0:16:52.560 --> 0:16:54.320 that hard to get rid of. You would think that 0:16:54.360 --> 0:16:59.520 this is a big, messy, slushy liquid that's molten hot, 0:17:00.040 --> 0:17:02.840 but in fact, liquid iron is very heavy and slag 0:17:02.880 --> 0:17:05.320 would float to the top, so you'd have the liquid 0:17:05.359 --> 0:17:08.040 iron underneath and the slag on top. When you are 0:17:08.119 --> 0:17:11.359 ready to draw off the molten iron, you would open 0:17:11.440 --> 0:17:14.800 up a tap hole located in the heart level of 0:17:14.840 --> 0:17:19.280 the blast furnace, so towards the base of this cylinder. 0:17:19.960 --> 0:17:25.320 And typically these taps also had a little gate on them, 0:17:25.440 --> 0:17:28.160 and the gate would go up and down, and by 0:17:28.200 --> 0:17:31.159 setting the gate at the right height, you can allow 0:17:31.400 --> 0:17:33.960 the molten iron to pass through and it would hold 0:17:34.000 --> 0:17:36.720 back the slag. So that way you just get the 0:17:36.720 --> 0:17:39.520 molten iron and the slag is left behind, because again 0:17:39.560 --> 0:17:42.600 the slag is floating at the top of this molten material. 0:17:43.440 --> 0:17:46.800 We'll be back with more about the Industrial Revolution after 0:17:46.880 --> 0:17:58.800 this quick break, so that molten iron would then run 0:17:58.840 --> 0:18:03.320 through a channel a trench essentially, and branch off into 0:18:03.400 --> 0:18:06.880 smaller channels on either side that acted as molds. So 0:18:07.600 --> 0:18:13.200 imagine that you've dug into some sand, uh some some 0:18:13.200 --> 0:18:17.879 some shapes for ingots, and you draw off this molten iron. 0:18:17.920 --> 0:18:21.000 It flows down a large channel and then splits off 0:18:21.040 --> 0:18:25.560 into these smaller channels that are inget molds. Essentially, that 0:18:25.640 --> 0:18:29.399 cooling iron would solidify into the ingots, and those ingots 0:18:29.440 --> 0:18:33.880 were called pigs and the iron is referred to as 0:18:34.000 --> 0:18:37.280 pig iron. And you might wonder, well, where did this 0:18:37.760 --> 0:18:40.080 name come from? Why is it pig iron? Is it 0:18:40.200 --> 0:18:43.520 dirty iron? What? What's the deal? Well, the reason for 0:18:43.640 --> 0:18:46.199 the name is that iron workers thought that the the 0:18:46.400 --> 0:18:51.000 little channels leading away from the central channel were similar 0:18:51.040 --> 0:18:54.920 to suckling piglets that were feeding from a sow. That 0:18:55.000 --> 0:18:59.399 the idea that these little splits, these channels were like piglets. 0:18:59.800 --> 0:19:04.959 And that's why it's called pig iron. I am not 0:19:05.040 --> 0:19:07.439 making that up. Pig iron is sort of a transitional 0:19:07.480 --> 0:19:11.160 point for usable iron. By the way, it's stronger than 0:19:11.240 --> 0:19:14.960 pure iron by about a hundred times, but it's still 0:19:15.000 --> 0:19:20.200 too weak to be of practical use for certain certain 0:19:20.440 --> 0:19:22.960 purposes like that, you can use it for tools and stuff, 0:19:22.960 --> 0:19:27.240 but you typically would use pig iron again by reheating 0:19:27.280 --> 0:19:30.760 it and doing something else with it. Now, the next 0:19:31.160 --> 0:19:34.919 basic type of iron after pig iron is cast iron, 0:19:34.960 --> 0:19:38.359 which is really not that different from pig iron. Uh. 0:19:38.400 --> 0:19:41.240 It's the stuff that the Darbies were making in their 0:19:41.320 --> 0:19:45.080 iron works. It has the same high carbon content around 0:19:45.200 --> 0:19:49.159 three to four percent as pig iron does. Now, there 0:19:49.200 --> 0:19:52.000 a lot of examples of stuff made from cast iron. 0:19:52.080 --> 0:19:55.240 Cast Iron skillets are probably my favorite version of something 0:19:55.280 --> 0:19:58.639 made from this material. And you would typically make a 0:19:58.880 --> 0:20:03.879 cast iron object by pouring the iron into a mold 0:20:04.040 --> 0:20:08.199 and allowing it to cool in that shape. And the 0:20:08.240 --> 0:20:11.119 reason you would want to do that is because cast 0:20:11.160 --> 0:20:14.520 iron is hard and it's brittle, which makes it very 0:20:14.600 --> 0:20:18.000 difficult to shape even when you heat it up. So 0:20:18.320 --> 0:20:22.240 if you pour the molten material into a mold so 0:20:22.280 --> 0:20:25.159 that it takes whatever shape you want and let it cool, 0:20:25.880 --> 0:20:28.320 you're in good shape. But if you let it cool 0:20:28.400 --> 0:20:31.160 at all and then you try and work with it, 0:20:31.160 --> 0:20:35.680 it tends to break, It tends to resist being being shaped, 0:20:36.200 --> 0:20:40.000 so it's not terribly useful. In that case. Um. So 0:20:40.680 --> 0:20:43.520 that's why it's called cast iron. It's best used if 0:20:43.560 --> 0:20:46.640 you cast it into molds. Cast iron, by the way, 0:20:46.680 --> 0:20:50.240 is also prone to rust, which made it less useful 0:20:50.280 --> 0:20:53.879 for material that was constantly exposed to the elements or 0:20:53.960 --> 0:20:57.920 was in damp areas. Now the next type of iron 0:20:58.119 --> 0:21:02.359 is wrought iron. To you are o U g HT 0:21:02.960 --> 0:21:06.600 wrought iron like a wrought iron fence. We produce wrought 0:21:06.600 --> 0:21:09.639 iron by taking pig iron and heating it up again 0:21:09.720 --> 0:21:13.840 in a different type of iron works called a finery. 0:21:14.000 --> 0:21:16.119 Now you'd heat the pig iron up to the liquid 0:21:16.160 --> 0:21:19.680 point and mix it with other slag materials, which lowers 0:21:19.760 --> 0:21:24.399 the carbon content. By introducing non carbon material you create 0:21:24.440 --> 0:21:28.240 a new alloy and the overall percentage of carbon is reduced. 0:21:28.280 --> 0:21:32.200 As a result, wrought iron is easier to work with 0:21:32.400 --> 0:21:35.920 than cast iron, and it's not as susceptible to rusting. 0:21:36.920 --> 0:21:39.399 Wrought iron ended up becoming the most important type of 0:21:39.440 --> 0:21:43.680 iron in the Industrial Revolution until people finally figured out 0:21:44.160 --> 0:21:48.960 how to make steel on a consistent and large scale basis. 0:21:49.000 --> 0:21:53.479 So wrought iron ended up being really the king of 0:21:53.520 --> 0:21:55.679 iron once people were able to do it on a 0:21:55.760 --> 0:22:00.960 large enough and consistent enough basis. So what's the big 0:22:00.960 --> 0:22:04.120 deal with steel? I mean, why wasn't Why wasn't steel 0:22:04.520 --> 0:22:08.399 the material of choice? Well, steel is just another alloy 0:22:08.440 --> 0:22:11.320 of iron. First of all, it's not like it's a 0:22:11.359 --> 0:22:15.520 totally different material. It's an alloy. It has less carbon 0:22:15.560 --> 0:22:18.040 in it than other types of iron, like I mentioned before, 0:22:18.240 --> 0:22:22.159 less than two and sometimes has other materials mixed in 0:22:22.280 --> 0:22:25.399 to create the steel. Different types of steel used different 0:22:25.440 --> 0:22:28.120 materials mixed in with the iron, and it gives it 0:22:28.640 --> 0:22:32.760 various properties. People have been making steel in small amounts 0:22:32.760 --> 0:22:35.840 for centuries. It's not like it was brand new in 0:22:35.880 --> 0:22:40.320 the Industrial Revolution. But it was a laborious process and 0:22:40.440 --> 0:22:42.879 it was easy to mess up. You could make errors 0:22:42.880 --> 0:22:46.920 that would produce iron rather than steel. For a long time, 0:22:47.560 --> 0:22:53.520 people weren't entirely uh certain of the what was causing 0:22:54.000 --> 0:22:57.800 the output to be steel versus iron. Sometimes they just thought, oh, well, 0:22:57.800 --> 0:23:00.639 this was a good batch of iron, or not realizing 0:23:00.680 --> 0:23:04.040 that the process they were using, or the materials they were, 0:23:04.040 --> 0:23:06.119 the fuel they were using, the materials they were mixing 0:23:06.160 --> 0:23:08.600 with it, we're actually making a huge difference. It took 0:23:08.640 --> 0:23:12.360 a long time of experimentation to figure out the right approach. 0:23:14.119 --> 0:23:19.080 One man who improved steel making techniques was Benjamin Huntsman, 0:23:19.480 --> 0:23:24.479 who opened a steel plant in Sheffield, England, in seventeen forty. 0:23:25.240 --> 0:23:28.600 His steel was kind of controversial actually at the time. 0:23:28.640 --> 0:23:31.800 His fellow countrymen considered the steel to be too hard 0:23:32.040 --> 0:23:36.119 to be useful. These were people called cutlers, who would 0:23:36.160 --> 0:23:40.560 take the steel produced by someone like Huntsman and then 0:23:40.680 --> 0:23:45.680 try and shape it into useful tools, often cutting tools. 0:23:45.680 --> 0:23:48.320 That was the main use of steel for a really 0:23:48.400 --> 0:23:52.320 long time. But the cutlers said, no, the steel is 0:23:52.359 --> 0:23:57.199 too hard, it's not any good. However, Huntsman began to 0:23:57.880 --> 0:24:02.320 form relationships with cutlers who were in Europe, not in England, 0:24:02.440 --> 0:24:06.320 so in mainland Europe, and they began to rely heavily 0:24:06.320 --> 0:24:08.640 on his steel and he started to do a lot 0:24:08.640 --> 0:24:13.080 of business. Well. England at the time was incredibly protective 0:24:13.280 --> 0:24:17.199 of its various industries. They wanted to preserve their dominance 0:24:17.800 --> 0:24:21.640 in as many areas as possible, including textiles and iron 0:24:21.880 --> 0:24:27.800 and uh and later on steam power. So because of that, 0:24:27.920 --> 0:24:33.359 the cutlers in England began to reconsider their feelings about 0:24:33.400 --> 0:24:37.840 the difficulty of working with Huntsman Steele, so they began 0:24:37.880 --> 0:24:40.360 to use it as well. Now Huntsman tried to keep 0:24:40.400 --> 0:24:43.120 his methods a secret. He was one of those people 0:24:43.119 --> 0:24:46.879 who decided never to patent his processes because he wanted 0:24:46.920 --> 0:24:51.040 to try and maintain full control over them. However, one 0:24:51.040 --> 0:24:55.320 of his competitors named Samuel Walker, found out how Huntsman 0:24:55.400 --> 0:24:59.440 was making his steel and began to copy him. According 0:24:59.480 --> 0:25:04.040 to report, Walker's work was never quite as good as Huntsman's, 0:25:04.119 --> 0:25:09.240 but his steel was also sought after, and so soon 0:25:09.480 --> 0:25:13.280 this technique of making steel began to spread outward and 0:25:13.359 --> 0:25:17.560 more iron workers began to experiment making steel, but at 0:25:17.560 --> 0:25:20.359