108 On the Decomposition and Composition 



ly performed, and in which no alkali adhered to the tube, 

 the basis of potash gained nearly two parts For, ten, and that 

 of soda between three and four parts. 



The results of the decomposition of water by the bases of 

 the alkalis were much more readily and perfectly obtained 

 than those of their combustion. 



To check the rapidity of the process, and, in the case of 

 potash, to prevent any of the basis from being dissolved, I 

 employed the amalgams with mercury. I used a known 

 weight of the bases, and made the amalgams under naph- 

 tha, using about two parts of mercury in volume to one of 

 basis. 



Tn the first instances I placed the amalgams under tubes 

 filled with naphtha, and inverted in glasses of naphtha, and 

 slowly admitted water to the amalgam at the bottom of the 

 glass ; but this precaution I soon found unnecessary, for the 

 action of the water was not so intense but that the hydrogen 

 gas could be wholly collected. 



I shall give an account of the most accurate experiments 

 made on the decomposition of water by the bases of potash 

 and soda. 



In an experiment on the basis of potash conducted with 

 every attention that I could pay to the minutiae of the ope- 

 rations, hydrogen gas, equal in volume to. 298 grains of 

 mercury, were disengaged by the action of *03 grains of the 

 basis of potash which had been amalgamated with about 

 three grains of mercury. The thermometer at the end of 

 the process indicated a temperature of 56° Fahrenheit, and 

 the barometer an atmospheric pressure equal to 29-6 inches. 



Now this quantity of hydrogen* would require for its 

 combustion a volume of oxygen gas about equal to that oc- 

 cupied by 154 - 9 grains of mercury, which gives the weight 

 of oxygen required to saturate the '08 grains of the basis of 

 potash at the mean temperature and pressure nearly '0151 

 grains. And '03 4- '0151 — -0951 : 'OS : : 100: 84' 1 nearly. 

 And according to these indications 100 parts of potash 

 consist of about 84 basis and IG oxygen. 



* Researches Chem. and Phil, page 287. 



In 



