PROCEEDINGS OF THE POLYTECHNIC ASSOUIATION. 545 



Mr. Rouse. — I do not. Flint is not fomid in this conntry at 

 all. 



Chairman. — Have you made any porcelain ? 



Mr. Rouse. — No, sir. There was some made about 25 years 

 ago, but it did not pay. 



The Chairman asked Dr. Stevens where the blue clay was 

 found ? 



Dr. Stevens said it was found in the southern part of Illinois, 

 North and South Carolina, Arkansas, Alabama, Mississippi, Red 

 River, Nebraska, New Jersey, Georgia, and other States. 



Mr. Rouse. — It requires great nicety to mix the different clays' 

 in making pottery. Too much of one clay might spoil the whole 

 composition. The material used for glazing costs eight cents per 

 pound, and that which we use we get from England. It is com- 

 posed of borax, whiting, and two other ingredients. Cups and 

 saucers are moulded in plaster of paris. 



Dr. Stevens. — Jersey clay contains silex, lime, and potash. If 

 it contains too much potash it runs. These clays are derived 

 from the decomposition of rocks. It underlies all Long Island, 

 and is found near the surface of the earth in Staten Island. It 

 is also found near Perth Amboy. The porcelain clay is what we 

 call felspar. The aluminous ston(?, unless well baked in the 

 earth, is much inclined to return to its original state. Silex, 

 lime and alumina makes a very good fire ware. One of the 

 greatest difficulties in getting clay fit for all kinds of ware is that 

 of getting it free from sulphate and sulphui et of iron. In New 

 Jersey there are beds of sunken wood so saturated in sulphate 

 and sulphuret of iron that on being exposed they become im- 

 mediately coated. 



Member. — Would the presence of lead and zinc add to its 

 adhesiveness ? 



Dr. Stevens. — I think it would act as a glazing power. 



Mr. Rouse. — I wish Dr. Stevens would suggest a way by which 

 we could get the iron out of the clay. 



Dr. Stevens. — That is nearly impossible to be done. I think at 

 this time that we make all the porous cups for batteries that are 

 used in this country and the Canadas. We have just executed 

 a very large order for the Grand Trunk Railway, and another 

 for the Montreal Railway. The directors of these railways have 

 stated that they have desisted buying from Europe, having 

 found that that whieh is manufactured in this country is the 



TAm. Inst.1 1 1 



