430
nder the pressure of the seal, so that troublesome corrections which would otherwise be entailed are avoided. After the carbide is completely decomposed, but not before two hours at least have elapsed, the cock p is shut, and the gasholder is run down to the zero mark by opening the cock q. The cock q is then shut, p is opened, and the analytical examination proper is begun by discharging the several carbide receptacles by turning the winch i. After the first receptacle has been discharged, five or ten minutes are allowed to elapse for the main evolution of gas to occur, and the cock p is then shut. Weights are added to the gasholder until the manometer n gives the zero reading; the position of the gasholder C is then read off, and readings of the barometer and of the thermometer o are made. The gasholder is then emptied down to the zero mark by closing the cock p and opening q. When this is done q is closed and p is opened, and the winch i is turned until the contents of the next carbide receptacle are discharged. This procedure is followed until the carbide from the last receptacle has been gasified; then, after waiting until all the carbide has been decomposed, but in any case not less than two hours, the position of the gasholder is read, and readings of the barometer and thermometer are again taken. The total of the values obtained represents the yield of gas from the sample examined."
The following example is quoted:
Weight of the tin received, with its contained | carbide . . . . . ._| = 6325 grammes. Weight of the empty tin . . . . = 1485 " _______ Carbide used . . . = 4840 " = 10670 lb.
The carbide in question was distributed among the nine receptacles and gasified. The readings were:
________________________________________________ | | | | | | No. | Litres. | Degrees C. | Millimetres. | |______|__________|______________|_______________| | | | | | | 1 | 152.5 |