SULPHURIC ACID FOR WATER. a 
ar temperatures. To effect this object, the 
experiments which I now commence relating 
were undertaken. 
EXPERIMENT I. 
I put into a glass evaporating dish of known 
weight 200 grains of sulphuric acid, sp. gr. about 
1.8428 ; and then intimately mixed therewith a 
little water, by which considerable heat was pro- 
duced.* After the dish and contents had been 
cooled by immersion for a short time in cold 
water, it was found, by weighing, that the quan- 
tity of water which I had added was 15 grains. 
Into another similar dish I put 200 grains of 
the acid, but did not add thereto any water. 
Both dishes were then immediately placed under 
an exhausted air-pump receiver. On the follow- 
ing day I re-weighed them, and found that the 
one into which the 15 grains of water had been 
put had gained 0.6 of a grain, and the other 1.2 
* It may be proper to observe, that the acid I used 
throughout my experiments was some which a friend of 
mine, Mr. H. Blair, an extensive manufacturer of the article, 
prepared for me with more than ordinary care, I found, by 
evaporation, that its total impurity amounted only to the 
1-20th of one per cent. And 100 grains gave with nitrate 
of barytes 233 grains of sulphate, = 79 real, or anhydrous 
sulphuric acid. 
