At present, the kerosene test, so far as the writer is concerned, is a misnomer, because raw linseed oil is used exclusively as giving more satisfactory results, and being less troublesome to apply.
I have here a length of the ordinary "heavy 4" commercial soil pipe, plain, and selected at random. Yesterday noon I had it oiled at my office, in order to be ready for to-night, and you see, by the chalk marks I have made, just where the leaks were and their area. I may say here that a sound pipe of this caliber and standard weight is the exception rather than the rule, and it was selected for this experiment merely to try and show the reaction a little better than the heavier pipe might.
Experiments of this nature I have carried along for the past two years, and I am glad to say that, since I began, the quality of the soil pipe furnished by the dealers for my work seems appreciably better than at first. Whether the poorer pipe is still made and sold to other customers I have no means of knowing; probably it is, however.
A large quantity of the pipe is now being tested at my suggestion by the Superintendent of Construction of the Johns Hopkins Hospital, at Baltimore. I have not yet heard the results from him, but doubtless they will be interesting. A brief summary of the results may be of some interest.
The different makers of soil pipe generally used by plumbers hereabouts are:
Mott & Company, Abendroth, Blakslee, Dighton, Phillips & Weeden, and Bartlett, Hayward & Co.
On 4" extra heavy pipe my results have been as follows:
Percentage passed as good, single hub. 60 per ct. to 70 per ct. Percentage passed as good, double. 20 per ct. to 80 per ct. Percentage passed special castings, including Y's and T's. 60 per ct.
Percentage passed as good, single hub. 25 per ct. to 35 per ct. Percentage passed as good, double. No record. Percentage special castings, including Y's and T's. 60 per ct.
It has been stated to me by dealers that the tar coating does away with the necessity of any such test as the oil; while I am not prepared to acknowledge or deny the statement, it is well known that much poor pipe is tar-coated and sold in the market as good, and when coated it is almost impossible to detect any but _very_ defective work.