abstracts: geochemistry 155 



instance, a silicate charge (2 grams) of specific heat 0.3, heated 10° per 

 minute, lagged 3° behind the furnace (G = 3°). Hence 3° in G corre- 

 sponds to 3 calories per minute. If an inversion absorbing 3 calories 

 and extending over 100° should occur, G would be increased 0.1, or 0.3° 

 for 10 minutes; if the inversion should take place in one minute, G would 

 be doubled, or increased 3°, etc. The detection of small heat-effects 

 is easier: (1) The larger G is, per calorie per minute, (2) the freer G 

 is from other variations, (3) the quicker the inversion occurs; it is only 

 sluggish inversions whose detection gives any trouble. 



G increases with the furnace-rate; hence a rapid rate is of the first im- 

 portance. G also increases with the diameter of the charge, but can be 

 made steadier in the case of a small charge, and the advantage of the 

 small charge appears to be greater on the whole. Fluctuations in the 

 furnace rate cause variations in G; these are partly eliminated by measur- 

 ing G, not between charge and furnace, but between the charge and 

 another body ("neutral body") closely resembling it. The apparatus 

 now used is small, two platinum crucibles holding 1 cc. each, 3 mm. 

 apart, and surrounded by a wider porcelain tube to increase uniformity 

 of temperature. A differential thermo-element is also used, which gives 

 directly the temperature difference of the two bodies at any instant. A 

 complete platinum inclosure shields the whole system from leakage 

 currents out of the furnace-coil. In one set of determinations made on 

 different days with the same set-up, conditions were reproduced over 

 a 300° interval with a maximum variation of from 0.03° to 0.06° in the 

 different determinations. This was with a silicate charge and indicates 

 that 1 calorie distributed over 100° could be detected. But this would 

 be a more difficult case than has yet been found in practice. In one case 

 it was observed that the first heating in each day which, of course, 

 occurred immediately after the furnace had been cold, gave results 

 differing by 0.3° from later heatings, altho the furnace was cooled 

 300° between all the heatings. This condition reproduced itself at 0.1° 

 on successive days and could, therefore, be largely eliminated, but might 

 prove decidedly deceptive if overlooked, and if the heat effect was, as 

 happens, one occurring only in the first heating. W. P. W. 



GEOCHEMISTRY. — The geochemical interpretation of water analyses. 



Chase Palmer. Bulletin U. S. Geological Survey No. 479. Pp. 



31. 1911. 



This paper presents a statement of water analyses in purely chemical 



terms; a general chemical formula representing water character in terms 



of the proportional reaction capacity of the constituents; a similar but 



