224 ACIDIF1ABLE COMBUSTIBLES. 



acid, though they were not attended with the 

 success which I had anticipated. 21*63 grains 

 of crystallized selenic acid heated till they be- 

 gan to sublime, and therefore considered as an- 

 hydrous, were dissolved in water, and crystallized 

 carbonate of soda in powder was added by small 

 quantities at a time, till the liquid began to give 

 a violet colour to cudbear paper. 43*43 grains 

 of the carbonate were necessary to produce this 

 effect. The liquid was now evaporated to dry- 

 ness, and the dry residuum exposed to a temper- 

 ature of about 600 on the sand bath, till it ceased 

 to give out moisture. It weighed 30-4 grains. As 

 it contained an excess of soda, the salt was 

 again dissolved in water, and a few drops of mu- 

 riatic acid being added, the whole was again 

 evaporated to dry ness. It now weighed 32| 

 grains, and, consequently, had increased in 

 weight 2'266 grains. 



This increase of weight was occasioned by the 

 union of the muriatic acid with the surplus soda. 

 No effervescence could be perceived, so that I 

 had no evidence that any carbonic acid had been 

 driven off. The salt having been exposed to heat, 

 it is obvious, that the common salt was converted 

 into chloride of sodium. The simplest way of 

 determining its quantity, will be to consider it a 

 compound of 3%5 muriatic acid and 4 soda. Now, 

 3%5 : 4 : : 2-266 (the augmentation of weight) : 

 2*59 = soda in the common salt. The common 



