884 Transactions of the American Institute. 



in its character; but, as a general thing, the discharge from sinks 

 will be alkaline, and the discharge from privies and water-closets will 

 be acid. 



One of the objections to cement pipes is that it is difficult to make 

 them endure acids and alkalies. It is almost impossible to glaze them 

 well, and it takes a long time for them to set, which, of course, 

 increases their expense. Without the glazing they can be made very 

 rapidly. Taking a mould of the right form, and leaving an annular 

 space, we put in a fat mixture of water and lime, which will set 

 rapidly, and ram it tightly, condensing it very firm and solid, and we 

 thus make a very good lime pipe. But it is liable to be destroyed 

 by acids. Yet I regard that as one of the hopeful lines of improve- 

 ment. 



Among the different kinds of pipe now in the market, baked pipes, 

 vitrified or coated, the imported "Scotch vitrified," and those made 

 here, stand among the best. Here is a pipe, made in Brooklyn, of 

 clay found in New Jersey, moulded by machinery, very strong and 

 tough. It requires evidently a good deal of expense first to mould them, 

 and then to dry and bake them uniformly. They must be stacked in 

 such a way as to be kept apart, and a good many will be imperfectly 

 baked or broken, which must be rejected. These are very good pipes ; 

 the only objection to them is their cost. They cost, for a nine-inch 

 pipe, about fifty-five cents per running foot. 



The Manhattan Compost Pipe Company have now built in Green- 

 point a large manufactory, just about starting, which proposes to 

 make a pipe adapted to resist all destructive influences, very strong, 

 with sufficient elasticity to withstand ordinary shocks, to bear freezing 

 up and thawing out again, which excels the best of our Scotch or 

 American baked pipe, at a cost, for nine-inch pipe, of about five cents 

 per foot. It is composed of sand cemented together with rosin, and 

 toughened. They take about seventy-five per cent of sharp, clean 

 sand, and five to seven per cent of pine rosin, about one-half per cent 

 of sulphur, which has a vulcanizing effect, and the rest is kaolin, fine 

 clay possessing considerable iron. This composition seems to set 

 before it gets cold, so that it is necessary to melt it and dispose of it 

 very rapidly. Instead of going through the ordinary process of 

 moulding, they adopt a process by which, an hour after it is moulded, 

 it is ready to be laid in the ground. The materials must all be at 

 hand, and they are put together by machinery, carrying them by rail- 

 way tracks. 



One difficulty to be overcome was the shrinking of the material. 



