WEBVTT - How the Industrial Revolution Worked, Part Two 0:00:04.200 --> 0:00:12.160 Get technology with tech Stuff from stolom. Hey there, and 0:00:12.280 --> 0:00:16.279 welcome to Tech Stuff. I'm your host, Jonathan Strickland. Now, 0:00:16.320 --> 0:00:19.600 in our last episode, we started to look at the 0:00:19.680 --> 0:00:25.000 beginning of the Industrial Revolution, which started in England in 0:00:25.040 --> 0:00:29.080 the mid eighteenth century. Though, as I mentioned in that 0:00:29.200 --> 0:00:33.080 previous episode, it's actually really hard to point at any 0:00:33.080 --> 0:00:36.720 historical event, not just the Industrial Revolution, but really any 0:00:36.800 --> 0:00:40.680 big event and definitively carve out exactly when it began, 0:00:41.560 --> 0:00:44.599 because history just doesn't work like that. Things develop and 0:00:44.720 --> 0:00:48.400 bleed into one another. But at any rate, generally speaking, 0:00:48.400 --> 0:00:51.760 we tend to look at seventeen seventeen fifties somewhere around 0:00:51.800 --> 0:00:56.120 there as the beginning of the Industrial Revolution. Now, in 0:00:56.160 --> 0:01:00.680 that last episode, I focused mainly on the textile industry 0:01:00.720 --> 0:01:03.880 because it's a great illustration of how quickly things changed 0:01:04.319 --> 0:01:07.320 just within a few decades and went from something that 0:01:07.400 --> 0:01:10.640 used to be a specialized skill among weavers that would 0:01:10.640 --> 0:01:14.360 do you know, maybe a couple would work together, uh, 0:01:14.640 --> 0:01:16.399 but that would be it, and it would be something 0:01:16.400 --> 0:01:19.039 that would be produced on a very small scale, to 0:01:19.440 --> 0:01:22.800 a full blown industry which would end up employing thousands 0:01:22.880 --> 0:01:26.880 of people. Now, in this week's episode, we're gonna look 0:01:26.920 --> 0:01:30.720 more closely at how iron shaped the Industrial Revolution and 0:01:30.760 --> 0:01:36.240 how innovations and inventions in the iron industry really changed things. 0:01:36.280 --> 0:01:40.280 And it's it's fascinating and also kind of complicated. Now, 0:01:40.319 --> 0:01:43.920 first of all, iron is the second most common metal 0:01:44.319 --> 0:01:48.360 in the Earth's crust. The most common would be aluminum. 0:01:49.040 --> 0:01:52.640 But we would never really use chemically pure iron, you know, 0:01:52.640 --> 0:01:57.720 the fe stuff to build anything of any significance. And 0:01:57.760 --> 0:02:00.880 that's because of a couple of things. Pure iron is 0:02:00.920 --> 0:02:03.720 really malleable, so that it means it's really easy to shape, 0:02:03.720 --> 0:02:08.359 so that's good. And you can even cut pure iron 0:02:08.600 --> 0:02:11.320 using something like a knife. If you've got a hunk 0:02:11.440 --> 0:02:14.880 of chemically pure iron, you can cut through it. It 0:02:14.919 --> 0:02:17.239 does take some effort, it's not like it's gonna slice 0:02:17.240 --> 0:02:20.359 through like butta, but you can do it. You can 0:02:20.480 --> 0:02:23.840 use a hammer to beat pure iron into sheets, or 0:02:23.960 --> 0:02:27.760 you can even draw it into wires. And it's great stuff. 0:02:27.760 --> 0:02:31.160 I mean, it conducts heat, it conducts electricity. It's also 0:02:31.320 --> 0:02:34.120 really easy to magnetize, so it's got a lot of uses. 0:02:35.080 --> 0:02:38.800 But it isn't strong or hard enough in order to 0:02:38.919 --> 0:02:43.359 use for building structures like bridges or buildings or canals 0:02:43.480 --> 0:02:47.560 or or even common tools. It's not strong enough to 0:02:47.560 --> 0:02:50.160 to do that. It will end up bending too too much. 0:02:50.560 --> 0:02:53.359 So all of that is kind of a moot point 0:02:54.160 --> 0:02:57.400 because there's something else about iron that gives it a 0:02:57.480 --> 0:03:01.799 huge drawback. We don't see much pure iron because it's 0:03:01.800 --> 0:03:06.640 got a habit of getting really familiar with oxygen. Oxygen 0:03:06.720 --> 0:03:10.880 corrodes iron, particularly in moist conditions, so that causes a 0:03:10.960 --> 0:03:15.519 chemical reaction in which pure iron forms an iron oxide 0:03:15.560 --> 0:03:19.440 that we call rust. So that's essentially what's happening, is 0:03:19.480 --> 0:03:23.520 this chemical reaction with iron and oxygen creates this iron 0:03:23.560 --> 0:03:27.359 oxide of rust that we don't really want. You know, 0:03:27.400 --> 0:03:29.560 there's always about you know, you have to scrub down 0:03:29.639 --> 0:03:31.200 the rust and get rid of it, or else it 0:03:31.280 --> 0:03:35.400 just continues to corrode. Well, because iron reacts so readily 0:03:35.440 --> 0:03:38.560 to oxygen, we don't mind iron in its pure form. 0:03:38.600 --> 0:03:40.640 In fact, we just we don't find it because it 0:03:40.720 --> 0:03:44.720 oxydizes so quickly. Instead, we mind iron oxides that are 0:03:44.760 --> 0:03:49.080 locked inside various types of ore, including hematite, which is 0:03:49.160 --> 0:03:54.000 the most plentiful ore that contains iron, limonite or limonite, 0:03:54.040 --> 0:03:56.080 depending on how you want to pronounce it, sometimes called 0:03:56.160 --> 0:04:00.440 bog iron and magnetite, which is also known as load stone, 0:04:00.520 --> 0:04:03.240 among others. There are a few other versions of iron 0:04:03.240 --> 0:04:06.640 ore as well. Not all ores contain the same percentage 0:04:06.640 --> 0:04:09.840 of iron by volume, and we mine iron both in 0:04:10.000 --> 0:04:13.480 underground mines and in surface mining. It all depends upon 0:04:13.560 --> 0:04:16.440 where you are and where the iron deposits. Happened to 0:04:16.480 --> 0:04:20.760 be now, the iron ore in Britain, because that again 0:04:20.960 --> 0:04:25.360 is where the Industrial Revolution began, had really high concentrations 0:04:25.400 --> 0:04:29.320 of sulfur and phosphorus, and both of those things will 0:04:29.400 --> 0:04:32.400 make iron brittle if you don't get rid of them. 0:04:32.880 --> 0:04:36.680 So until the Industrial Revolution, iron masters hadn't really quite 0:04:36.760 --> 0:04:39.840 worked out how to do that on an efficient basis. 0:04:40.839 --> 0:04:43.560 For that reason, British iron was often used in very 0:04:43.680 --> 0:04:47.960 cheap items like nails. Now, this was also a little 0:04:47.960 --> 0:04:51.599 tricky because iron making iron required a lot of labor, 0:04:51.640 --> 0:04:55.200 a lot of backbreaking hard work, and that drove up 0:04:55.240 --> 0:04:58.760 the price of the final product. So Britain was starting 0:04:58.800 --> 0:05:03.880 to supplement its own iron supplies by importing about half 0:05:03.920 --> 0:05:06.840 of all the iron that was using from Sweden. The 0:05:06.920 --> 0:05:10.240 iron from Sweden did not have the high concentrations of 0:05:10.279 --> 0:05:14.640 sulfur or phosphorus, so it wasn't as problematic, and Britain 0:05:14.680 --> 0:05:17.680 just couldn't produce enough of its own despite ample supplies 0:05:17.720 --> 0:05:21.440 of iron ore. Now, once we get hold of iron ore, 0:05:22.120 --> 0:05:25.120 we have to smelt it. That's in order for us 0:05:25.120 --> 0:05:27.520 to get to the iron that's inside of it. Now, 0:05:27.520 --> 0:05:30.440 this involves heating the ore up to the melting point 0:05:30.520 --> 0:05:34.880 of iron. We also use fuels that will produce chemicals 0:05:34.880 --> 0:05:38.520 that can bond with the iron during this process, which 0:05:38.720 --> 0:05:44.440 changes iron's physical characteristics. We're talking chemical reactions here, and 0:05:44.440 --> 0:05:48.120 what we're really doing is creating iron alloys. And an 0:05:48.160 --> 0:05:51.760 alloy is a mixture that has a metal with something else. 0:05:51.800 --> 0:05:54.640 Sometimes it's another metal, sometimes it's a different substance. But 0:05:54.720 --> 0:05:58.800 these are chemical mixtures that have their own features that 0:05:59.040 --> 0:06:04.320 are a front from the features of the individual elements 0:06:04.839 --> 0:06:08.880 or or ingredients in that mixture, so you're getting something new. 0:06:09.880 --> 0:06:13.680 The main ingredient we mix with iron to produce useful 0:06:13.760 --> 0:06:16.560 material is carbon, and if you get the mix of 0:06:16.600 --> 0:06:20.360 carbon to iron just right, you produce steel. Steel is 0:06:20.400 --> 0:06:25.120 an iron alloy that has around two or less carbon 0:06:25.279 --> 0:06:27.880 in it. Other types of iron hab between two to 0:06:27.960 --> 0:06:30.800 four percent of carbon in the alloy, and mixing other 0:06:30.880 --> 0:06:34.640 metals or substances will create different types of steel or iron. 0:06:35.600 --> 0:06:40.479 So how do you mix carbon into the iron? What 0:06:40.600 --> 0:06:43.240 exactly are you doing here is there's some sort of 0:06:44.080 --> 0:06:46.440 powder that you're pouring in. Well, one way is by 0:06:46.520 --> 0:06:51.080 using a carbon rich fuel as the means of heating 0:06:51.120 --> 0:06:53.640 up your iron to melt it in the first place. 0:06:53.680 --> 0:06:55.479 So if you're using something a fuel that has a 0:06:55.480 --> 0:06:58.360 lot of carbon in it, then some of that carbon 0:06:58.360 --> 0:07:02.800 gets transferred into the iron as it melts. Charcoal is 0:07:02.800 --> 0:07:07.679 a great example, and iron masters in Britain and really 0:07:08.000 --> 0:07:12.080 all over Europe relied very heavily on charcoal for centuries 0:07:12.120 --> 0:07:15.760 when smelting iron ore. But if you remember from our 0:07:15.840 --> 0:07:19.280 last episode, I talked about a man named Abraham Darby 0:07:19.440 --> 0:07:23.280 who came up with an alternative to charcoal, and it 0:07:23.360 --> 0:07:27.400 was coke. Now, coke is a fuel product you make 0:07:27.920 --> 0:07:31.400 by baking coal in an airless oven or furnace at 0:07:31.440 --> 0:07:35.640 a really high temperature, and at that high temperature, some 0:07:35.760 --> 0:07:38.640 of the coal begins to ash. That ash will end 0:07:38.760 --> 0:07:43.360 up melding with the the coal itself and it converts 0:07:43.400 --> 0:07:47.720 into this other fuel called coke, which is once it 0:07:47.760 --> 0:07:51.360 cools down, grayish in color and has a very porous structure. 0:07:51.680 --> 0:07:56.280 When you burn coke, it creates carbon monoxide, among other things, 0:07:56.280 --> 0:08:00.400 which is important in this process of creating iron useful iron. 0:08:01.680 --> 0:08:04.680 But why would anyone worry about switching from charcoal to 0:08:04.760 --> 0:08:07.280 coke in the first place. I mean, charcoal is pretty simple. 0:08:07.320 --> 0:08:10.800 You just have to burn wood to make charcoal. Uh. 0:08:10.840 --> 0:08:14.080 And in fact, this is where the problem would come in. 0:08:14.080 --> 0:08:20.040 In order to fuel a single iron works for one year, 0:08:20.600 --> 0:08:24.480 it would take two acres of forest to supply enough 0:08:24.560 --> 0:08:29.240 charcoal for operations. So for one iron works, you would 0:08:29.240 --> 0:08:32.560 need two hundred acres of woods. And keep in mind 0:08:32.640 --> 0:08:35.320 that once you've gone through that that two acres of 0:08:35.360 --> 0:08:38.160 forests in a year, you're not gonna be able to 0:08:38.240 --> 0:08:41.199 use those same two hundred acres the next year because 0:08:41.200 --> 0:08:44.000 it's going to take time for that forest to grow back. 0:08:44.880 --> 0:08:49.079 So we saw a steady decrease in the forests of 0:08:49.120 --> 0:08:52.959 Britain during this time period. At this time, iron works 0:08:52.960 --> 0:08:56.600 were mostly located in forests because it was cheaper to 0:08:56.679 --> 0:08:59.880 ship the iron ore and iron from the iron work 0:09:00.160 --> 0:09:02.000 or to the iron works, and from the iron works 0:09:02.360 --> 0:09:06.520 then it was to ship charcoal around, so they located 0:09:06.520 --> 0:09:09.240 the iron works near the fuel, not the iron ore, 0:09:09.440 --> 0:09:14.640 which seems counterintuitive at first, but eventually the growth of 0:09:14.640 --> 0:09:18.559 the iron industry and the fact that more and more 0:09:19.559 --> 0:09:23.320 people were building ships during this time period for England 0:09:23.880 --> 0:09:25.959 meant that England was using up more wood than it 0:09:26.000 --> 0:09:30.839 could replenish. So charcoal became more expensive because forests were 0:09:30.840 --> 0:09:35.080 being chopped down. Wood was becoming a scarce commodity comparatively 0:09:35.160 --> 0:09:38.040 speaking compared to how it had been in previous centuries, 0:09:38.559 --> 0:09:41.760 so it became really expensive to use forests just to 0:09:41.800 --> 0:09:45.960 generate charcoal. So an alternative fuel was definitely needed to 0:09:46.120 --> 0:09:51.680 make British iron and actual commodity. Now. Some iron masters 0:09:51.720 --> 0:09:56.720 tried using coal as fuel, but burning coal produces sulfur, 0:09:56.960 --> 0:09:59.800 and that sulfur would react to the melted iron ore 0:09:59.840 --> 0:10:01.760 and produce an iron that was too brittle to be 0:10:01.840 --> 0:10:06.400 of much use. Coke, however, didn't produce nearly as much 0:10:06.440 --> 0:10:10.120 sulfur when burned, and the carbon monoxide coke produces when 0:10:10.160 --> 0:10:12.360 burned would mix with a melted iron ore to create 0:10:12.520 --> 0:10:16.120 useful iron. And if you listen to that last episode, 0:10:16.760 --> 0:10:19.800 you heard that Abraham Darby had developed a process for 0:10:19.920 --> 0:10:23.000 making pig iron by using coke as the fuel. While 0:10:23.120 --> 0:10:27.000 smelting iron ore, but his approach wasn't adopted by the 0:10:27.040 --> 0:10:30.760 iron industry during his lifetime. There are a couple of 0:10:30.800 --> 0:10:34.040 reasons for that that, you know, the iron industry didn't 0:10:34.080 --> 0:10:37.959 immediately swap to using coke instead of charcoal. One of 0:10:38.000 --> 0:10:41.640 those reasons is that Darby pretty much kept his process 0:10:41.640 --> 0:10:46.360 a secret and only told his son, Abraham Darby the second, 0:10:46.559 --> 0:10:49.959 how to do it. At the time, anyone wanted to, 0:10:50.160 --> 0:10:52.400 you know, get an advantage over their competitors. What they 0:10:52.400 --> 0:10:55.200 did was they kept their methods secret. Some people would 0:10:55.240 --> 0:10:58.680 choose to patent ideas to protect them. Others decided that 0:10:58.720 --> 0:11:02.000 patents were bad because if you if you file a patent, 0:11:02.240 --> 0:11:05.280 the information on how you do something becomes public knowledge 0:11:05.840 --> 0:11:10.199 and eventually passes into the public domain. So rather than 0:11:10.280 --> 0:11:13.079 patent of process, some people would try and keep it 0:11:13.160 --> 0:11:16.800 a secret. That's what Derby did. But the other reason 0:11:16.840 --> 0:11:19.640 is that Darby didn't live to a very ripe old age. 0:11:19.720 --> 0:11:23.480 He actually had a really long illness and died at 0:11:23.559 --> 0:11:29.400 age thirty eight in seventeen seventeen. Now, his grandson, Abraham 0:11:29.480 --> 0:11:32.840 Derby the third would build the first iron bridge in 0:11:32.880 --> 0:11:36.640 the late seventeen seventies, but the Derby's method was really 0:11:36.640 --> 0:11:39.640 only good for creating a particular type of iron called 0:11:39.880 --> 0:11:42.840 cast iron. And I'll talk more about what cast iron 0:11:42.960 --> 0:11:46.640 is in just a minute, but first, let's talk about 0:11:46.720 --> 0:11:50.040 the smelting process, all right. So let's say you've got 0:11:50.080 --> 0:11:53.440 yourself an iron furnace. Typically we would talk about a 0:11:53.480 --> 0:11:59.400 blast furnace. Blast furnaces are really giant cylinders. We're talking 0:11:59.600 --> 0:12:02.080 some of them being around thirty to forty ft tall 0:12:02.160 --> 0:12:06.400 and to thirty ft square at the base. Often built 0:12:06.760 --> 0:12:10.360 into the side of a hill. So that way, in 0:12:10.440 --> 0:12:14.640 order to bring materials to the blast furnace, which you 0:12:14.640 --> 0:12:18.360 would deposit in the top of the furnace, you would 0:12:18.520 --> 0:12:21.480 climb the hill, as opposed to putting scaffolding up or 0:12:21.520 --> 0:12:23.800 a long ramp or however you would you know, be 0:12:23.920 --> 0:12:26.120 able to have an access point to get to the 0:12:26.160 --> 0:12:29.520 top of the furnace. Now, if you want to imagine 0:12:29.520 --> 0:12:32.040 what these things look like, they did like a look 0:12:32.120 --> 0:12:35.360 like a tapering cylinder. So the top is a bit 0:12:35.480 --> 0:12:40.000 narrower than the bottom. Uh the topmost portion of the 0:12:40.040 --> 0:12:42.760 cylinder is called the shaft, and that's where you would 0:12:42.800 --> 0:12:46.400 feed the fuel, the iron ore and some other materials 0:12:46.440 --> 0:12:50.600 called flux, which is typically limestone. The purpose of the 0:12:50.640 --> 0:12:54.400 flux is to absorb some of the other elements inside 0:12:54.400 --> 0:12:58.160 the iron ore that you don't want corrupting your iron. 0:12:58.240 --> 0:13:01.160 You don't want it to uh mixed with the iron 0:13:01.320 --> 0:13:04.439 so that it makes it have properties that you weren't intending. 0:13:05.000 --> 0:13:09.040 So you've got your your flux, your fuel in this 0:13:09.080 --> 0:13:12.280 case coke or charcoal, and in the iron ore itself. 0:13:13.360 --> 0:13:15.720 You would put all that down the shaft. If you 0:13:15.840 --> 0:13:19.640 look down the cylinder, then the next section is called 0:13:19.880 --> 0:13:25.640 the bosch. This is a roughly circular chamber where uh 0:13:25.840 --> 0:13:29.679 it gets incredibly hot. And below the bosch, at the 0:13:29.720 --> 0:13:34.400 base of the blast furnace was the hearth or crucible, 0:13:34.440 --> 0:13:37.080 and that's where the molten iron would accumulate before being 0:13:37.160 --> 0:13:39.960 drawn off by the iron master. Drawn off just means 0:13:40.000 --> 0:13:46.840 essentially drained from the furnace chamber. So this was actually 0:13:46.880 --> 0:13:50.600 a pretty complicated process. Uh. In fact, they were called 0:13:50.600 --> 0:13:54.920 blast furnaces because you would blow large drafts of air 0:13:55.360 --> 0:13:59.280 into the furnace and what we're called blasts. The earliest 0:13:59.280 --> 0:14:03.160 blast furnaces where cold air furnaces, meaning that the the 0:14:03.280 --> 0:14:06.600 air being blown into the furnace had not been preheated 0:14:06.600 --> 0:14:09.400 in any way. The air would typically be forced through 0:14:09.440 --> 0:14:12.360 an entry point that's down the cylinder. It's not at 0:14:12.360 --> 0:14:16.960 the top, so you're not blowing air down into a chimney. Rather, 0:14:17.040 --> 0:14:20.640 you would have an entry point inside the furnace and 0:14:20.800 --> 0:14:23.640 air would come in there towards the bottom. You want 0:14:23.680 --> 0:14:27.640 it near the bottom to fan the flames, and that 0:14:27.680 --> 0:14:29.680 would allow you to keep the fire burning at the 0:14:29.760 --> 0:14:33.000 right temperature. And you would do this with an enormous 0:14:33.200 --> 0:14:38.080 set of bellows. So you've probably seen bellows. These are 0:14:38.160 --> 0:14:44.040 the devices made to actually blow air into a an area, 0:14:44.160 --> 0:14:48.440 usually some form of furnace or fire that would provide 0:14:48.440 --> 0:14:50.960 the blast of air. And in the early Industrial Revolution 0:14:51.000 --> 0:14:53.640 they were powered by a water wheel. And when I 0:14:53.720 --> 0:14:56.120 say an enormous pair of bellows, I mean we're talking 0:14:56.640 --> 0:15:00.000 a big, big piece of machinery. They would be more 0:15:00.040 --> 0:15:03.200 than twenty ft long and four or five ft wide, 0:15:04.160 --> 0:15:08.880 So these were huge and would create very powerful blasts 0:15:08.960 --> 0:15:12.280 of air. Now, later iron masters would actually rely upon 0:15:12.400 --> 0:15:15.640 steam engines to power a blower for the furnace. But 0:15:15.680 --> 0:15:18.400 we'll talk more about steam engines towards the end of 0:15:18.400 --> 0:15:23.480 this episode. So if you wanted to start up in ironworks. 0:15:23.960 --> 0:15:26.440 You've just you've just decided to get into the business, 0:15:26.560 --> 0:15:30.600 and you're an eighteenth century England, then what you would 0:15:30.640 --> 0:15:34.240 need to do is build your blast furnace in a 0:15:34.280 --> 0:15:38.240 in a good location, get all the stuff ready, like 0:15:38.280 --> 0:15:41.080 the bellows and everything all prepared, and then you would 0:15:41.120 --> 0:15:43.680 need to get your furnace up to the right temperature 0:15:44.080 --> 0:15:49.080 before you actually started to add iron ore. Uh. You 0:15:49.600 --> 0:15:52.800 would do this in a process that was called blowing in. 0:15:53.760 --> 0:15:56.200 Now that involved bringing a large amount of fuel into 0:15:56.240 --> 0:15:59.480 the furnace, whether it's charcoal or coke or whatever. You 0:15:59.520 --> 0:16:01.880 would have to ignite the fuel and allow it to 0:16:02.440 --> 0:16:06.560 gradually heat the furnace over about a week's worth of time, 0:16:07.520 --> 0:16:10.400 and once it was up to the proper temperature, you 0:16:10.400 --> 0:16:13.080 could finally get started with iron working. And when you're 0:16:13.080 --> 0:16:16.160 ready to smell iron, you feed the fuel, flux and 0:16:16.240 --> 0:16:19.000 iron ore into the top of the furnace. You're essentially 0:16:19.080 --> 0:16:24.160 dumping things down this the cylinder, this chimney. Now, as 0:16:24.200 --> 0:16:26.720 those materials fall through the length of the furnace, they 0:16:26.760 --> 0:16:29.000 begin to heat up. There's a lot of very hot 0:16:29.080 --> 0:16:32.880 gases that are rising up through this cylinder, and the 0:16:32.920 --> 0:16:36.280 material passes through those hot gases getting hot before they 0:16:36.320 --> 0:16:41.160 even get toward the heart the crucible, the fuel begins 0:16:41.200 --> 0:16:44.240 to burn and the iron starts to heat up to 0:16:44.360 --> 0:16:47.760 melting temperature. The iron ore reacts with the charcoal or 0:16:47.760 --> 0:16:50.960 the coke, and that absorbs the oxygen in the iron 0:16:51.000 --> 0:16:54.240 oxide that was locked away inside the iron ore. Now 0:16:54.280 --> 0:16:57.800 this is a process called reduction. And while you're left 0:16:57.840 --> 0:17:02.400 with is liquid iron and slag. Slag is actually not 0:17:02.440 --> 0:17:04.199 that hard to get rid of. You would think that 0:17:04.240 --> 0:17:09.520 this is a big, messy, slushy liquid that's molten hot, 0:17:09.880 --> 0:17:12.720 but in fact liquid iron is very heavy and slag 0:17:12.760 --> 0:17:15.200 would float to the top, so you'd have the liquid 0:17:15.240 --> 0:17:17.920 iron underneath and the slag on top. When you are 0:17:18.000 --> 0:17:21.240 ready to draw off the molten iron, you would open 0:17:21.320 --> 0:17:24.679 up a tap hole located in the heart level of 0:17:24.720 --> 0:17:29.200 the blast furnace, so towards the base of this cylinder. 0:17:29.840 --> 0:17:35.120 And typically these taps also had a little gate on them, 0:17:35.320 --> 0:17:38.040 and the gate would go up and down, and by 0:17:38.080 --> 0:17:41.080 setting the gate at the right height, you can allow 0:17:41.280 --> 0:17:43.879 the molten iron to pass through and it would hold 0:17:43.920 --> 0:17:46.600 back the slag. So that way you just get the 0:17:46.600 --> 0:17:49.400 molten iron and the slag is left behind. Because again 0:17:49.440 --> 0:17:52.480 the slag is floating at the top of this molten material, 0:17:53.359 --> 0:17:56.320 So that molten iron would then run through a channel 0:17:57.160 --> 0:18:01.000 a trench essentially, and branch off into smaller channels on 0:18:01.080 --> 0:18:05.120 either side that acted as molds. So imagine that you've 0:18:05.200 --> 0:18:12.240 dug into some sand, uh some some some shapes for ingots, 0:18:12.280 --> 0:18:15.520 and you draw off this molten iron. It flows down 0:18:15.600 --> 0:18:18.720 a large channel and then splits off into these smaller 0:18:18.800 --> 0:18:23.120 channels that are inget molds. Essentially, that cooling iron would 0:18:23.160 --> 0:18:27.359 solidify into the ingots, and those ingots were called pigs 0:18:28.680 --> 0:18:32.280 And the iron is referred to as pig iron. And 0:18:32.320 --> 0:18:35.200 you might wonder, well, where did this name come from? 0:18:35.200 --> 0:18:38.080 Why is it pig iron? Is it dirty iron? What? 0:18:38.240 --> 0:18:40.919 What's the deal? Well, the reason for the name is 0:18:40.920 --> 0:18:44.400 that iron workers thought that the the little channels leading 0:18:44.440 --> 0:18:48.920 away from the central channel were similar to suckling piglets 0:18:48.960 --> 0:18:52.280 that were feeding from a sow. That the idea that 0:18:52.320 --> 0:18:56.800 these little splits, these channels were like piglets. And that's 0:18:56.800 --> 0:19:02.280 why it's called pig iron. I am not making that up. 0:19:02.440 --> 0:19:05.320 Pig iron is sort of a transitional point for usable iron. 0:19:05.400 --> 0:19:09.480 By the way, it's stronger than pure iron by about 0:19:09.520 --> 0:19:12.360 a hundred times, but it's still too weak to be 0:19:12.920 --> 0:19:18.080 of practical use for certain certain purposes like that. You 0:19:18.119 --> 0:19:20.680 can use it for tools and stuff, but you typically 0:19:20.680 --> 0:19:24.760 would use pig iron again by reheating it and doing 0:19:24.800 --> 0:19:28.679 something else with it. Now, the next basic type of 0:19:28.720 --> 0:19:32.720 iron after pig iron is cast iron, which is really 0:19:32.760 --> 0:19:35.800 not that different from pig iron. Uh. It's the stuff 0:19:35.840 --> 0:19:39.119 that the Darbies were making in their iron works. It 0:19:39.160 --> 0:19:42.400 has the same high carbon content around three to four 0:19:42.480 --> 0:19:46.080 percent as pig iron does. Now there are a lot 0:19:46.119 --> 0:19:49.200 of examples of stuff made from cast iron. Cast iron 0:19:49.240 --> 0:19:52.199 skillets are probably my favorite version of something made from 0:19:52.200 --> 0:19:56.960 this material. And you would typically make a cast iron 0:19:57.000 --> 0:20:01.160 object by pouring the iron into a mold and allowing 0:20:01.200 --> 0:20:05.280 it to cool in that shape. And the reason you 0:20:05.280 --> 0:20:08.439 would want to do that is because cast iron is 0:20:08.560 --> 0:20:11.800 hard and it's brittle, which makes it very difficult to 0:20:11.920 --> 0:20:15.280 shape even when you heat it up. So if you 0:20:15.480 --> 0:20:19.280 pour the molten material into a mold so that it 0:20:19.320 --> 0:20:22.680 takes whatever shape you want and let it cool, you're 0:20:22.800 --> 0:20:25.119 in good shape. But if you let it cool at 0:20:25.160 --> 0:20:27.960 all and then you try and work with it, it 0:20:28.000 --> 0:20:32.280 tends to break. It tends to resist being being shaped, 0:20:32.800 --> 0:20:36.600 so it's not terribly useful in that case. Um, So 0:20:37.280 --> 0:20:40.119 that's why it's called cast iron. It's best used if 0:20:40.160 --> 0:20:43.240 you cast it into molds. Cast iron, by the way, 0:20:43.280 --> 0:20:46.840 is also prone to rust, which made it less useful 0:20:46.880 --> 0:20:50.480 for material that was constantly exposed to the elements or 0:20:50.560 --> 0:20:54.520 was in damp areas. Now, the next type of iron 0:20:54.720 --> 0:20:59.800 is wrought iron w r o U g HT wrought 0:20:59.800 --> 0:21:03.520 eye like a wrought iron fence. We produce wrought iron 0:21:03.560 --> 0:21:06.399 by taking pig iron and heating it up again in 0:21:06.480 --> 0:21:10.760 a different type of iron works called a finery. Now 0:21:10.760 --> 0:21:13.000 you'd heat the pig iron up to the liquid point 0:21:13.080 --> 0:21:16.439 and mix it with other slag materials, which lowers the 0:21:16.520 --> 0:21:21.159 carbon content. By introducing non carbon material you create a 0:21:21.200 --> 0:21:24.840 new alloy and the overall percentage of carbon is reduced. 0:21:24.880 --> 0:21:28.800 As a result, wrought iron is easier to work with 0:21:29.000 --> 0:21:32.520 than cast iron, and it's not as susceptible to rusting. 0:21:33.480 --> 0:21:36.000 Wrought iron ended up becoming the most important type of 0:21:36.040 --> 0:21:40.240 iron in the Industrial Revolution until people finally figured out 0:21:40.760 --> 0:21:45.560 how to make steel on a consistent and large scale basis, 0:21:45.600 --> 0:21:50.479 So wrought iron ended up being really the king of iron. 0:21:50.520 --> 0:21:52.600 Once people were able to do it on a large 0:21:52.680 --> 0:21:57.720 enough and consistent enough basis. So what's the big deal 0:21:57.760 --> 0:22:01.920 with steel? I mean, why wasn't why steel the material 0:22:01.960 --> 0:22:05.440 of choice? Well, steel is just another alloy of iron. 0:22:05.520 --> 0:22:09.160 First of all, it's not like it's a totally different material. 0:22:09.400 --> 0:22:12.680 It's an alloy. It has less carbon in it than 0:22:12.720 --> 0:22:15.240 other types of iron, like I mentioned before, less than 0:22:15.280 --> 0:22:19.320 two and sometimes has other materials mixed in to create 0:22:19.359 --> 0:22:23.080 the steel. Different types of steel used different materials mixed 0:22:23.119 --> 0:22:26.240 in with the iron, and it gives it various properties. 0:22:26.960 --> 0:22:30.359 People have been making steel in small amounts for centuries. 0:22:30.720 --> 0:22:33.639 It's not like it was brand new in the Industrial Revolution, 0:22:33.720 --> 0:22:37.600 but it was a laborious process and it was easy 0:22:37.640 --> 0:22:40.159 to mess up. You can make errors that would produce 0:22:40.240 --> 0:22:44.840 iron rather than steel. For a long time, people weren't 0:22:45.040 --> 0:22:51.200 entirely uh certain of the what was causing the output 0:22:51.240 --> 0:22:54.400 to be steel versus iron. Sometimes they just thought, oh, well, 0:22:54.400 --> 0:22:57.240 this was a good batch of iron, or not realizing 0:22:57.280 --> 0:23:00.200 that the process they were using, or the material else 0:23:00.240 --> 0:23:02.239 they were, the fuel they were using, the materials they 0:23:02.240 --> 0:23:04.840 were mixing with it, we're actually making a huge difference. 0:23:04.880 --> 0:23:08.040 It took a long time of experimentation to figure out 0:23:08.040 --> 0:23:13.520 the right approach. One man who improved steel making techniques 0:23:14.000 --> 0:23:19.200 was Benjamin Huntsman, who opened a steel plant in Sheffield, England, 0:23:19.359 --> 0:23:24.679 in seventeen forty. His steel was kind of controversial actually 0:23:24.720 --> 0:23:27.440 at the time. His fellow countrymen considered the steel to 0:23:27.520 --> 0:23:31.639 be too hard to be useful. These were people called cutlers, 0:23:31.720 --> 0:23:36.360 who would take the steel produced by someone like Huntsman 0:23:36.880 --> 0:23:41.439 and then try and shape it into useful tools, often 0:23:41.520 --> 0:23:44.439 cutting tools. That was the main use of steel for 0:23:44.520 --> 0:23:48.320 a really long time. But the cutlers said, no, the 0:23:48.400 --> 0:23:53.160 steel is too hard, it's not any good. However, Huntsman 0:23:53.280 --> 0:23:57.800 began to form relationships with cutlers who were in Europe, 0:23:58.119 --> 0:24:01.560 not in England, so in in mainland Europe, and they 0:24:01.640 --> 0:24:04.800 began to rely heavily on his steel and he started 0:24:04.800 --> 0:24:07.000 to do a lot of business. Well. England at the 0:24:07.080 --> 0:24:12.000 time was incredibly protective of its various industries. They wanted 0:24:12.040 --> 0:24:16.120 to preserve their dominance in as many areas as possible, 0:24:16.160 --> 0:24:21.760 including textiles and iron and uh and later on steam power. 0:24:22.560 --> 0:24:26.639 So because of that, the cutlers in England began to 0:24:26.760 --> 0:24:32.600 reconsider their feelings about the difficulty of working with Huntsman Steele, 0:24:33.520 --> 0:24:36.280 so they began to use it as well. Now, Huntsman 0:24:36.359 --> 0:24:39.280 tried to keep his methods a secret. He was one 0:24:39.280 --> 0:24:42.240 of those people who decided never to patent his processes 0:24:42.720 --> 0:24:46.880 because he wanted to try and maintain full control over them. However, 0:24:47.440 --> 0:24:51.320 one of his competitors named Samuel Walker found out how 0:24:51.400 --> 0:24:55.520 Huntsman was making his steel and began to copy him. 0:24:55.560 --> 0:24:59.560 According to reports, Walker's work was never quite as good 0:24:59.600 --> 0:25:05.000 as Huntsman's, but his steel was also sought after, and 0:25:05.119 --> 0:25:08.600 so soon this technique of making steel began to spread 0:25:08.680 --> 0:25:13.119 outward and more iron workers began to experiment making steel, 0:25:13.240 --> 0:25:15.679