356 Analysis of the Hot Sprhig; at Bath. 



To account for the great difference of these results, Dr- 

 Saunders has supposed that the water varies at different tinie.^, 

 or that the residuum has heen dried with various degrees of 

 heat. I have ascertained the quantity of the contents of the 

 water several times during ahout eighteen months, without 

 observing anv other variation in its weight than is unavoida- 

 ble in experiment. In support of this observation it may 

 be remarked, tliat I found its speciiic gravity exactly as stated 

 by Dr. Falconer. 



It is scarcely probable that the results of any of these 

 analyses were obtained by drying the residuum at a lower 

 temperature than Qlti^, or at a greater than a rexl heat. Now 

 I find that one quart of the water, weighing 30 troy ounces 

 172gfairis, at the temperature of 03'% gives 32 grains of 

 residuum dried at 212": when the heat of a sand-bath is 

 employed, 30 grains are obtained ; and at a red heat, 28 

 grains. The greatest variation afforded by these methods is 

 four grains ; whereas from some cause, which it is difficult 

 to explain, the extreme diff'ererjce of the experiments above 

 cited is ] 6^ grains. When a red heat is employed, a part 

 of the loss is occasioned by the decomposition of the carbo- 

 nate of lime; for water poured upon the residuum turns 

 turmeric paper of a reddish brown colour. The greater part 

 of the residuum is perfectly white ; the portion deposited at 

 the upper part of the vessel is, however, slightly greyish, 

 but not at all appearing as if coloured by oxide of iron. I 

 suspected that it might be occasioned bv carbonaceous mat- 

 ter : to ascertain whether this was the case, the following 

 experiment was made : 



(f) Four pints of the water were evaporated to dryness in 

 a retort, and the residuum boiled with about live ounces of 

 alcohol. The filtered solution left, on evaporation, 8*3 grains 

 of a yellowish-coloured substance. A part of this was dis- 

 solved in water, and afforded a copious white precipitate with 

 nitrate of silver, but did not give any with ammonia or with 

 carbonate of ammonia : nuu-iate of soda was therefore the 

 only salt dissolved by the alcohol. 



{ui) To the remaining portion of the saline mass colour- 

 less sulphuric acid was added. By heating, the acid acquired 



a dark 



