PROCESS OF MANUFACTURE. 151 



tains all the phosphoric acid there was in the bones. The 

 ammonia is gone ; it has run off in the vapors that were 

 thrown off by the action of the fire underneath, into a coil of 

 pipes, and from these into a tank, where the bone-coal, and 

 the ammonia with it, are treated with acid, and the sulphate 

 of ammonia is precipitated to the bottom. 



Now, I have shown you where we get three of the materi- 

 als which go to make up the phosphates. If you have 

 observed closely, you have noticed that these three materials 

 are all of them waste materials, for the cost of all the other 

 things that we manufacture is reckoned without reckoning 

 that waste, and if we can sell that at a profit, we are lucky. 

 Every manufocturer knows that if a man can get his waste 

 products for nothing, it is so much added to his profits. 



We have now three of the materials that go to make the 

 phosphates. Now, we have a contract with the Providence 

 and Pawtucket meat dealers, by which Ave obtain the offal 

 from their butcher-shops. We have two car-loads of it every 

 day. Well, what is that? It is the insides of cattle, sheep 

 and hogs, and everything in the Avay of offal, and the hair. 

 The hair is put one side, and sold as another merchantable 

 article ; the tripe goes to another place. The rest of this 

 stuff is put into a rendering tank, sealed closely, and the 

 tallow is rendered away ; that goes to Liverpool. After Ave 

 get that done the rest is concentrated right down, and treated 

 with sulphuric acid, when it becomes a homogeneous mass, 

 and then it is shovelled out one side. Then we have got 

 another product. 



We go another step. After we have used up all the bone 

 we can for bone-coal, there still remain some bones, Avhich 

 are broken up, put into a vat, and steamed, AA'ith the steam at 

 a high pressure. After they have been steamed a sufficient 

 time, those bones become softened, to a considerable extent ; 

 the* tallow is dipped off, and put aAvay and sold in another 

 place, and then the bones are in splendid condition to take 

 the acid, which is run through the bones, and dissolves them. 



NoAv we Avant to make the phosphate, and Avhat do Ave do? 

 We take a certain portion of this biphosphate of lime, Avhich 

 has been made by the action of the acid upon the bones ; Ave 

 add to this a certain portion of the biphosphate (I may call it 



