420 W. F. Hillebrand — Zinc-hearing Spring Waters, 



Besides the above tabulated constituents the waters held a 

 considerable quantity of organic matter, which was not esti- 

 mated, a small amount of ammonia not exceeding one part per 

 million and which if counted as sulphate would affect only 

 slightly the relative proportions of calcinm sulphate and car- 

 bonate, and in an unconcentrated state they gave no reaction 

 with brucine or diphenylamine for nitrates or nitrites. Al- 

 though cadmium was not found in the water from the West 

 Spring, it is possible, in view of the close similarity of the two 

 waters, that it was somehow overlooked. 



In analyzing these waters a peculiarity deserves to be men- 

 tioned, which may at the same time serve as a warning to any 

 one who may in the future examine them. Although a por- 

 tion of the calcium unquestionably exists as carbonate, as shown 

 by the excess of bases over chlorine and sulphuric anhydride, 

 it is nevertheless the case that all the carbon dioxide is ex- 

 pelled by simply boiling the water. The amounts found for 

 the East and West springs respectively were 120 -5 and 110*0 

 parts of C0 2 per million. ISTo more was obtained by acidify- 

 ing the water. At the same time a precipitation of a zinc 

 compound free from carbon dioxide and from calcium began 

 to take place in the water as soon as the boiling point was 

 neared, which soon ceased after ebullition set in. This pre- 

 cipitation furnishes the explanation of the total escape of car- 

 bon dioxide combined as well as free, from the unacidulated 

 water; for as the calcium bicarbonate in solution becomes 

 decomposed by heat the calcium carbonate at temperatures 

 near the boiling point at once reacts with zinc sulphate with 

 the formation of calcium sulphate, zinc hydrate or a very 

 basic sulphate, and carbon dioxide. A determination of total 

 solid constituents by evaporation of the water to dryness 

 would involve therefore a very serious error in addition to 

 those usually encountered. 



A few remarks are here necessary in connection with the 

 above reaction, which in one particular is so contrary to the 

 statements which have come under my observations in chemi- 

 cal and geological literature bearing on the reaction which takes 

 place between zinc salts in aqueous solution and undissolved 

 calcium carbonate at elevated temperatures. It is generally 

 stated that a basic zinc carbonate is precipitated while calcium 

 sulphate goes into solution, except by Demarcay, the discoverer 

 of the reaction, who says,* that zinc oxide is thrown down. It 

 is not to be supposed that soluble calcium in the form of bicar- 

 bonate would in any way affect this reaction except to hasten its 

 completion. While a zinc carbonate is undoubtedly thrown down 



*Ann. d. Cliemie, toI. xi, p. 250, 1834. 



