Combination of Sulphuric Acid and Water. 259 



degrees, was marked by means of a watch, which pointed 

 out seconds. Every trial was repeated three times. After the 

 experiments were concluded, the whole results were com- 

 pared together, and where any anomaly occurred two other 

 repetitions took place. The numbers given in the follow- 

 ing table are always the mean of at least three experi- 

 ments, and four of them are the mean of five experiments. 

 Hence, it is presumed, that the numbers given denote, with 

 very considerable accuracy, the time which acid of each 

 strength took to cool 40°, the commencement of cooling 

 always taking place when the heat of the liquid was 80° 

 above that of the room in which the experiments were 

 made. The time occupied with these experiments was 

 about eight weeks, from the 16th of May to about the 12th 

 of July, and the thermometer in the room varied from 

 59° to 67°. 



Time of cooling 40°. 



Empty Flask, 215''-5 



Water, 5720-7 



1 atom acid + 1 wat 



-f 

 + 

 + 

 ■f 

 + 



+ 

 + 



2 

 3 



4 

 5 

 6 

 7 

 8 

 9 

 10 



er. 



3860 



4837-7 



4587-2 



4702-7 



4831-7 



4967-3 



5075 



5164-3 



5267-7 



5307-5 



It will be observed in looking over this table, that 

 24 cubic inches of a compound of (1 atom acid + 2 atoms 

 water) took a longer time to cool 40° than acid composed of 

 1 atom acid H- 3 atoms water 

 1 „ +4 



1 „ +5 



This was so unexpected an occurrence, that I repeated 

 the experiment six times and varied the acid to guard against 

 any accidental alteration ; but still the anomaly continued. 

 I then determined the specific heat by mixing a pound of 

 hot glass in powder, with a pound of the cold acid, and 

 observing the alteration of the temperature. But, not- 



s2 



