SANITATION 69 



freely, when they are replaced. The weight of the float is so 

 adjusted by the makers that no greater pressure can be applied 

 without forcing the smoke out at the cover than can be resisted by 

 the water trap of ordinary depth. 



The Hydraulic Test. With the hydraulic test the outlet of a 

 drain, or a section of it, is plugged with an expanding rubber bag 

 or other patent stopper and the section to be tested then filled with 

 water to a pressure of a head of from 6 to 10 feet. The water is 

 left in for two or three hours and if a leak exists its presence is 

 indicated by a fall in the head of water at the point of observation. 

 A dry day should be chosen on which to make the test. It will be 

 obvious that the pressure at the outlet end of a big system will be 

 much greater than at the higher level. For this reason some objec- 

 tion is taken to the hydraulic test, it being alleged that the test 

 should be most severe at the house or stable connections. This, 

 however, is no conclusive argument, as the greatest strain on a 

 drainage system is at the distal end where a choke is most likely to 

 occur. 



The Smell Test. An old method was to pour oil of peppermint 

 down the drain followed by hot water. If there is a leak in the 

 system the smell of the peppermint would be detected. An im- 

 proved method of applying this test is by a special apparatus intro- 

 duced through the seal of a trap, which liberates after it has passed 

 the seal a mixture of calcium carbide and asafoetida. Should there 

 be a leak a most pungent and penetrating odour is soon detected. 

 While the smell test for routine practice is not now generally used 

 it has its special advantages for certain situations, as, for instance, 

 at the top of a tenement building far removed from actual drains 

 where it is desired to try the joints and fittings of that particular 

 house. Kinzett's Patent Drain Tester is the most useful for this 

 purpose. 



DRAINAGE SYSTEMS FOR ANIMAL HABITATIONS. There are two 

 systems of drainage: (1) Surface Drains and (2) Underground 

 Drains. A surface drainage system is one where the matter to 

 be conveyed away is carried in open channels on the surface of the 

 ground. Underground drains carry the effluent in pipes out of 

 sight under the soil. 



Until comparatively recent times it was the custom to use under- 

 ground drains for the interior of all animal houses, and especially 

 in stables. This system has been superseded by the surface method. 

 With the old system it was the custom in the case of a stable to have 

 a pipe running the length of the building behind the stalls and for 

 the urine of each stall to trickle through a trap into the pipe. In 



