222 Mr. Braade qh the Analysis 



g The presence of muriatic salts and of chlorides, is indicated 

 by a white cloud on adding sulphate of silver. 



h The sulphates, when present in water, afford a white preci- 

 pitate on the addition of nitrate of baryta, which is insoluble 

 in nitric acid. 



i Lime is recognised by a white cloud on dropping oxa- 

 late of ammonia into the water. A portion of the precipi- 

 tate collected upon leaf platinum, and heated before the blow- 

 pipe, may be burned into quicklime. 



k Magnesia is rendered evident by adding carbonate of, 

 ammonia which throws down the lime, and subsequently pour- 

 ing in phosphate of soda, which, when magnesia is present, 

 carries a portion of it down in the form of a granular precipi- 

 ta,te of ammoniaco-magnesian phosphate. 



Such are the readiest means of recognising the presence of 

 the various substances that commonly occur, by the action of 

 re-agents or tests ; and, having gained such general informatiop, 

 we next proceed to the analysis of the water, in order to ascer- 

 tain the relative proportions of the gaseous and saline ingre- 

 djlents )vhich it holds dissolved. 



Section III. Analysis of Mineral Waters. 



5. To ascertain the relative proportions of the gaseous contents 

 of water with perfect accuracy, is a very difficult undertaking, 

 and rarely necessary; the following method is sufficiently pre- 

 cise in all ordinary cases of analysis. Provide a Florence flask 

 capable of holding rather more than a measured "vvine pint, 

 which quantity of the water under examination is to be intro- 

 duced into it, and a cork carefully fitted to its neck, through 

 a perforation in which is inserted a glass-tube one-eighth inch 

 diameter, rising perpendicularly about eighteen inches, and then 

 bent so as to pass conveniently under the shelf of the mercurio- 

 pneumatic apparatus. (Where a sufficiency of mercury cannot be 

 procured, warm water may be substituted, if only carbonic acid 

 be present, and it may be absorbed by transferring the jar con- 

 taiping it to a solution of potassa.) The flask should be placed 

 over an argand lamp, and heat gradually applied till the water 



