$12, Mode 9f analyzing [Book VII. 



tended to is the degree of the heat of the water, and 

 for this purpofe it is neceffary to be provided with an 

 accurate thermometer. There are many fprings 

 which have a temperature a little above the medium 

 temperature of the atmofphere, though this may not 

 be fo remarkable as to have obtained them the name 

 of hot fprings. The middle temperature of thefe 

 fprings is found to be about forty-eight degrees, but 

 on elevated fituations it is lefs, in proportion to their 

 height .above the fea. It may alfo be proper to com- 

 pare the temperature of theie mineral fprings with 

 that of fome common fprings in the neighbourhood. 

 The fenfible qualities, as the colour, tafte, and fmell, 

 are to be obferved. In order to difcover whether any 

 elaflic fluid efcapes from it, and of what nature it is, 

 let fome of the water be put into a bottle, and a blad- 

 der tied about its neck. The air which efcapes may 

 be fubmitted to examination. In order to obtain it, 

 it is only neceiTary to tie another firing above the bot- 

 tle, and then to cut between them, fo as to fcparate 

 the bladder, which may be plunged in water or mer- 

 cury, and its contents received in the pneumatic appa- 

 ratus. In order to feparate all the air from water, it 

 mull be heated nearly to its boiling point, which may 

 eafity be done by immerfing it in a vefTel of boiling 

 water, while it is contained in the bottle to which the 

 bladder is annexed. The elaftic fluids, which may be 

 feparated from mineral waters, are chiefly two, carbonic 

 acid gas, and fulphureous gas. It is proper to obferve 

 the changes which are fpontaneoufly produced on mi- 

 neral waters by different degrees of heat. If any mat- 

 ter is depofited during the evaporation of the mine- 

 ral water, it muft be collected for further examina- 

 tion. 



With reflect to the addition of certain foreign fub- 



ftances 



