J. P. Cooke— New Mode of Manipohdini, Hyh-ic Sulphide. 433 



line, to drive out all the air originally in the apparatus, as well 

 as the free hydrogen subsequently evolved. Moreover, in the 

 preparation of the solution of hydric sulphide, the generator 

 should be much larger relatively to the fountains than in the 

 preparation of soda-water. Thus we use for charging the 

 so-called six-gallon steel fountains, the "Upright Generator," 

 known as No. 40, which has a capacity below the diaphragm 

 of sixty liters. It should be here stated that the fountains an 

 only rated at two-thirds of their total capacity, which is the 

 volume of soda-water which is ordinarily made in them. They 

 should never be more than three-fourths filled with water. 

 But, even with this liberal allowance for gas room, the six- 

 gallon fountains referred to will hold twenty-five liters of 

 water. It may also be stated, although the fact must be evi- 

 dent, that a single large fountain will not give as good results 

 as several small ones of equal capacity ; since in expelling the 

 air and free hydrogen, as we have described, there would be a 

 considerable loss of material, if only one fountain were used. 

 Still, in laboratories where the consumption is not great, the 

 loss is not important ; and the smallest " Upright Generator, 

 with one six-gallon fountain, will be found to be a perfectly 

 satisfactory apparatus. 



Assuming first that the larger apparatus is used, the method 

 of charging is as follows : The large generator is too heavy to 

 be readily moved, and should be placed so that the discharge 

 valve will empty directly into a drain. Water also should be 

 brought to the apparatus by hose,— if possible, both hot and 

 cold water— not only for convenience in charging, but also in 

 washing. Finally, there ought to be a good flue in the neigh- 

 borhood, into which the waste gas may be discharged, lne 

 apparatus having been thus established, the three fountains- 

 first rinsed out— are filled each with twenty-five liters ot dis- 

 tilled water, and the valves having been secured, the fountains 

 are connected with each other and the generator by means ot 

 stout rubber hose as already indicated, and the vent valve of 

 the last fountain is connected with the flue by a length of com- 

 mon gas hose. The generator is then charged as follows : I tie 

 handle is first placed so as to uncover the bungs and cover the 

 slits in the diaphragm. Through the bung A is now poured 

 forty liters of hot water, heated to between v0° and 80 C, and 

 then five liters of common oil of vitriol are P ™. ^ ^ 

 tiously into the same bung through a lead funnel with narrow 

 spout provided for the puW The / Cld ^^fS^W 

 heated nearly to the boiling point, and its capacity of ^^ 



to pass through a wire sieve with eight meshes to the inch, and 



