ARTIFICIAL CHELTENHAM WATER. 143 



test gave no indication of the presence of lead, which has 

 been suspected to be contained in soda manufactured in this 

 way. The quantity I would recommend is two scruples, or 

 forty grains troy, for the half pint of water. The carbo- 

 nate of magnesia I made use of I prepared myself from 

 sea water, and therefore I could depend upon its purity. 

 The quantity for the same dose of water is one scruple, or 

 twenty grains: the half of the quantity of the soda. The 

 sulphuric acid I employ is the dilute acid of the Edinburgh 

 College; of the specific gravity of 1-0735, and was formed, 

 by adding one' part (by weight) of the strong acid of com- 

 merce, of the specific gravity of 1*852, to eight parts of 

 water. The quantity of this acid I use is 250 grains by 

 measure, or a quantity equal in bulk to 250 grains of water. 

 In this proportion, there is a slight deficiency of sulphuric 

 acid, which should always be observed ; for the excess of 

 carbonic acid will be able to dissolve any carbonate of mag- 

 nesia that may remain, and any excess of sulphuric acid 

 gives the water a harsh disagreeable taste, and might injure 

 the teeth, or affect the bowels, if irritable. The volume of 

 carbonic acid gas disengaged by these quantities is about 35 

 cubic inches, and in a half pint bottle is equal to the active 

 pressure of an additional atmosphere and a half on the sides 

 of the bottle, or to two atmospheres and a half upon the 

 surface of the water. The sulphuric acid is best to be di- 

 luted, as by this any errour in measuring will be diminished, 

 and by dilution it throws down a sediment, which often con- 

 tains a portion of lead. 



As the carbonate of soda is unsteady in the quantity of Indication of 

 water it contains, being affected by the dryness or humidity d " ficienc y °{ 

 of the atmosphere, and the sulphuric acid of commerce is 

 not always of the same strength, it may happen, that the 

 quantity of the acid I have here specified shall not exactly 

 answer : if so, any excess will manifest itself by an acid 

 taste in the water after it has stood some time exposed to 

 the air in an open vessel; and any great deficiency of acid, 

 by the whole of the magnesia not being dissolved. In this 

 case the quantity of acid must be increased or diminished 

 as indicated. But I would advise every person, who would The proper 

 wish to give this process a fair trial, to appreciate by expe- £ggJ >ortlons . 



riment 



