The Smoke Test is also a very good test. It is applied as follows: by means of bellows, or some exploding, smoke-producing rocket, smoke is forced into the system of pipes, the ends plugged up, and the escape of the smoke watched for, as wherever there are defects in the pipes the smoke will appear. A number of special appliances for this test are manufactured, all of them more or less ingenious.
The Scent Test is made by putting into the pipes a certain quantity of some pungent chemical, like peppermint oil, etc., the odor of which will escape from the defects in the pipes, if there are any. Oil of peppermint is commonly used in this country for the test. The following is the way this test is applied: all the openings of the pipes on the roof, except one, are closed up tightly with paper, rags, etc. Into the one open pipe is poured from two to four ounces of peppermint oil, followed by a pail of hot water, and then the pipe into which the oil has been put is also plugged up. This is done, preferably, by an assistant. The inspector then proceeds to slowly follow the course of the various pipes, and will detect the smell of the oil wherever it may escape from any defects in the pipes. If the test is thoroughly and carefully done, if care is taken that no fixture in the house is used and the traps of same not disturbed during the test, if the openings of the pipes on the roofs are plugged up tightly, if the main house trap is not unsealed (otherwise the oil will escape into the sewer), and if the handling of the oil has been done by an assistant, so that none adheres to the inspector—if all these conditions are carried out, the peppermint test is a most valuable test for the detection of any and all defects in plumbing. Another precaution to be taken is with regard to the rain leader. If the rain leader is not trapped, or if its trap is empty, the peppermint oil may escape from the pipes into the rain leader. Care must be taken, therefore, that the trap at the base of the rain leader be sealed; or, if no trap is existing, to close up the connection of the rain leader with the house drain; or, if this be impossible, to plug up the opening of the leader near the roof.
Instead of putting the oil into the opening of a pipe on the roof, it may be put through a fixture on the top floor of the house, although this is not so satisfactory.
Various appliances have been manufactured to make this test more easy and accurate. Of the English appliances, the Banner patent drain grenade, and Kemp's drain tester are worthy of mention. The former consists "of a thin glass vial charged with pungent and volatile chemicals. One of the grenades, when dropped down any suitable pipe, such as the soil pipe, breaks, or the grenade may be inserted through a trap into the drain, where it is exploded." (Taylor.) Kemp's drain tester consists of a glass tube containing a chemical with a strong odor; the tube is fitted with a glass cover, held in place by a string and a paper band. When the tester is thrown into the pipes and hot water poured after it, the paper band breaks, the spring opens the cover, and the contents of the tube fall into the drain.
Recently Dr. W. G. Hudson, an inspector in the Department of Health of New York, has invented a very ingenious "peppermint cartridge" for testing plumbing. The invention is, however, not yet manufactured, and is not on the market.
CHAPTER X
Infection and Disinfection
Disinfection is the destruction of the infective power of infectious material; or, in other words, disinfection is the destruction of the agents of infection.
An infectious material is one contaminated with germs of infection.