SULPHURIC ACID FOR WATER. 359 
over the whole surface of the bottoms, were left 
exposed to the atmosphere in a room without fire. 
They were re-weighed every morning during the 
continuance of the experiment, and several times 
moved about every day to agitate the contents. 
The temperature and vapour point of the room 
were accurately ascertained, and registered three 
times a day.* On the 4th October, each dish 
was found to have lost 3.2 grains, and on the 5th 
4.3 grains; on the 6th each was found to have 
regained 0.2 of a grain, and on the 7th their 
weights were exactly the same as on the 6th. In 
each case, therefore, the weight of the diluted 
acid on the 6th and 7th, was 4.1 grains less than 
when put into the dish. The loss of water was 
41 per cent; the liquid remaining in each dish 
being 5.9 grains. If we suppose 100 grains of 
the diluted acid to have been used in this experi- 
ment instead of 10, they would have been reduced 
to 59 grains, those 59 grains containing all the 
anhydrous sulphuric acid which was in the 100 
grains of the diluted acid experimented upon, 
viz. 15.8 grains ;f the per centage, therefore, of 
* The vapour point was ascertained by Dr. Dalton’s 
method. 
t By treating 100 grains of this diluted acid with nitrate 
of barytes, I obtained 46.7 grains of sulphate, = 15.8 anhy- 
drous sulphuric acid. 
