129 



prepared and analysed in several different ways. Ist, 10 grains, 

 precipitated by nitrate of baryta, gave 18-31 grains of sulphate of 

 baryta, theory requires 18-33 grains; while, for the hydrated bisul- 

 phate, 17*12 grains would be the quantity. 2d, 12*72 grains in a 

 second experiment gave 23-24 baryta salt, theory 23-32. 



2d, 12-72 grains of the salt were carefully introduced into a hard 

 glass tube, and an excess of freshly-ignited oxide of lead added, but 

 so as not to come in contact with the salt, the tube with its contents 

 was then carefully weighed, and heated to redness so as to fuse both 

 substances, but no loss of weight could be detected; the hydrated 

 salt would have lost about 0-8 grains. 



3d, 1272 grains of the salt were dissolved in hot water, and 

 slightly coloured with litmus; to this was added a solution of 5-32 

 grains of recently-ignited carbonate of soda in a measured quantity 

 of water ; the whole of this, being the calculated quantity, was re- 

 quired to restore the blue colour to the hot solution coloured by the 

 litmus. 



4th, The whole of the eight specimens were tested as to their 

 neutralising powers by means of the same solution of caustic soda, 

 and found to agree ; there can therefore be little doubt that the an- 

 hydrous bisulphate of potash can be easily got, and of definite com- 

 position. 



Having thus endeavoured to shew that the anhydrous bisulphate 

 of potash can be obtained of definite neutralising power, little need 

 be said w^th regard to its application, as it is intended merely as a 

 substitute for the sulphuric acid used in Peligot's process, and that 

 entirely on account of the ease with which its quantity may be deter- 

 mined by weighing alone, without the necessity of having recourse 

 to any mode of analysis, as is indispensable when any acid solution 

 is made use of. One other advantage may be mentioned — the salt 

 is neither deliquescent nor hygroscopic, for when 10 grains in fine 

 powder were exposed in the laboratory during the night in an open 

 watch-glass, they had not gained -001 grain by the morning. 



In employing the salt in an analysis, any convenient quantity is 

 weighed out and dissolved in warm water in a beaker-glass, and 

 slightly coloured with litmus ; a part of this solution is then intro- 

 duced into the bulb-tube, and made use of in the analysis ; after- 

 wards it is returned to the beaker-glass, and neutralised with solution 

 of caustic soda ; the difference between the quantity of soda required, 



