W. F. Hillebrand — Zinc-bearing Spring Waters. 421 



from a solution of the chloride by calcium carbonate, or by the 

 bicarbonate as I have satisfied myself by experiment, this does 

 not seem to be the case with a solution of zinc sulphate. An ex- 

 periment, tested by repetition, with zinc sulphate and calcium 

 bicarbonate in about the proportions shown in the above 

 waters, i. e. with insufficient carbonate to throw out all the 

 zinc, by observing which precaution no calcium carbonate can 

 contaminate the precipitate, showed that the latter was abso- 

 lutely free from carbonic acid and from calcium, but contained 

 some sulphuric acid. If this is the normal reaction for the 

 sulphate it is the one to be chiefly considered by the geologist, 

 for in nature the sulphate of zinc and not the chloride, on 

 which latter laboratory experiments seem to have been largely 

 made, is the form in which that element is most likely to be 

 found in solution. 



The sediments from the bottles, which were very slimy, 

 amounted when dried at 100° C. to approximately 17"0 parts 

 per million of the water from the East Spring and to about 

 403 parts per million of that from the West Spring. They 

 contained thus dried not less than 13 per cent of water and 

 organic matter, while the ignition residue was about three 

 fourths silica, and the remainder zinc oxide with a little iron, 

 alumina, and sulphuric acid. The sediments were undoubtedly 

 a mixture of amorphous silica, with very basic sulphates of 

 zinc, aluminum and iron, without calcium. They had in both 

 cases probably formed after the water was bottled, for they 

 continued to appear in that portion of the filtered water which 

 was retained as a reserve till completion of the analysis. As 

 the two waters were not analyzed simultaneously the analyses 

 are not strictly comparable, for one had deposited more sedi- 

 ment than the other, but it is noticeable that the water richest 

 in salts had also deposited most sediment, showing that the 

 differences in the analyses are not solely or in the main due to 

 the different lengths of time that had elapsed between bottling 

 and analyzing, but to inherent differences in composition. 



With the waters was sent in a separate small bottle a sample 

 of the precipitate deposited in the depression into which the 

 springs emptied. It was contaminated by much decaying 

 vegetable matter and admitted of no satisfactory quantitative 

 examination, but after filtration and washing, qualitative tests 

 showed it to be essentially the same as the deposit found in the 

 bottles. Owing to its greater amount it was also possible to 

 ascertain that cadmium, lead, and copper were to a certain 

 extent concentrated in it. 



The source of the metallic salt constituents of these waters 

 is of course to be sought in one of the deposits of zinc blende 



Am. Jour. Sol— Third Series, Vol. XLIII, No. 251.— Mat, 1892. 

 28 



