434 J. P. Cooke— New Mode of Manipulating Hydric Sulphide. 



mixed with two kilograms of marble powder — is run through 

 a wide-mouth funnel into the bung B. The bungs having been 

 now all closed, the joints of the apparatus tested, the exit valve 

 D of the generator and all the valves of the fountains opened, 

 a small amount of the powder is sifted down into the acid 

 water by turning the handle not more than a single revolution, 

 always taking care to leave it so that the slits of the diaphragm 

 shall" be left covered. The gas is then allowed to stream 

 through the apparatus, and tested as it escapes into the flue, 

 until it burns without explosion, using a small pneumatic 

 trough for that purpose. The air is now nearly expelled, and 

 the escape of gas should be reduced by the last vent valve 

 until the current only supplies a small jet, which may now be 

 attached and lighted with safety, and by the size of this flame 

 the vent may afterwards be regulated. The handles are now 

 slowly turned, and the pressure in the apparatus carried up to 

 about 120 pounds. The valves of the fountains and the valve' 

 D of the generator are now all closed, and the two last foun- 

 tains detached, leaving the first (which is mounted on a frame 

 as represented in Fig. 1) united to the generator as before. 

 This is now rocked for several minutes to and fro, in order to 

 thoroughly agitate the water with the gas. The stop valve G 

 should then be opened, and then the valve D (very gr 

 so that the gas may be admitted slowly to the fountain. The 

 valves are then again closed, and the agitation renewed, and 

 the same operation is repeated several times until no more gas 

 is absorbed by the water in the fountain, the pressure in the 

 generator meanwhile being maintained at 120 pounds, by turn- 

 ing the handle. The first fountain is then removed, and the 

 same process repeated with each of the others. At the close 

 of the operation, after all chemical action has eeas 

 remains in the generator— both free and dissolved in the liquid 

 residue— a large volume of hydric sulphide gas. This we 

 economize by venting the generator slowly through Woolf s 

 bottles containing aqua ammonia, and thus preparing at the 

 same time ammonic sulphide. It is not unimportant to add 

 that the generator should be emptied before it cools, and the 

 ferrous sulphate has time to crystallize. The discbarge valve 

 R should then be removed, and the whole apparatus thor- 

 oughly washed out. If the valve becomes clogged, it can 

 generally be cleared by developing pressure in the 

 by means of a small charge of ground marble. Otherwise, 

 after the pressure has been relieved, and the upper valves and 

 bungs closed, the discharge valve must be cautiously removed, 

 and an opening forced through the lower bung. So 

 are necessary in order that others may profit by our experi- 

 ence ; but, lest the details should convey the impression thai 



