Chemistry and Physics. 411 



crystalline mass of dark red sulphide showing a metallic luster. 

 In a current of hydrogen, the sulphide yielded pure germanium 

 having all the properties of the metal obtained from argyrodite. 

 The amount present in euxenite is about one-tenth of one per cent. 

 — Ber. Berl. Chem. Ges., xxi, 131, Jan., 1888. G. f. b. 



3. On the Double Acetate of calcium a,nd copper. — Rudorff 

 has prepared and analyzed anew the large quadratic crystals de- 

 scribed first by Brewster. They were prepared by dissolving 25 

 grams copper acetate and 66 grams calcium acetate in 350 c.c. of 

 water, moderately heated. On cooling the crystals separated. 

 Upon analysis they gave the formula CaCu(C 2 H 3 2 ) 4 . (H 2 O) ; 

 and not (H 2 0) 9 as determined by Ettling. — Ber. Berl. Chem. Ges., 

 xxi, 279, Feb. 1888. G. f. b. 



4. JJeber die ReaMionsgeschioindigkeit zwischen islandischem 

 JDoppelspat und einigen Sauren. — A recent number of that excel- 

 lent new journal, the Zeitschrift fur physhalische Chemie (vol. ii, 

 p. 13), contains an interesting article by W. Spring on the rapidity 

 with which Iceland Spar is attacked by certain acids, in continu- 

 ation of an earlier article in which marble was the substance in- 

 vestigated. The surfaces exposed to the acid were the cleavage 

 planes, and also planes cut parallel and perpendicular to the 

 vertical axis. At a temperature of 15° it was found that the 

 surfaces parallel to the axis dissolved with sensibly the same 

 velocity as the cleavage planes, but this equality disappeared as 

 the temperature rose and at 35° and 55° the reaction was 1*23, 

 1*28 times more rapid. In the case of the surfaces normal to the 

 axis at 15° the rapidity of solution was greater but did not in- 

 crease so rapidly with increase of temperature. In taking the 

 ratio of the velocity of solution for the vertical and transverse 

 surfaces at the different temperatures the number 1*14 is obtained 

 'as the mean, which, it is interesting to note, is not far from the 

 relation of the two refractive indices to each other (viz : 1*115). 

 In other words the author establishes a relation between chemical 

 activity and optical elasticity. 



5. The Integral Weight of Water ; T. Sterry Hunt. — In a 

 paper on Chemical Integration published in this Journal for 

 August, 1887, and reprinted in the Chemical JYeios, Sept. 23d and 

 30th, it was said that in comparing the densities of liquid and 

 solid bodies with those of known gaseous species , such as water- 

 vapor and carbon dioxyd, " or in the last analysis with the density 

 of the hydrogen unit, ... we get the specific gravity of these 

 bodies, the dyad integer of hydrogen at 0° and 760 mm (H 2 = 2'0) 

 being unity." Subsequently, in a paper on Integral Weights in 

 Chemistry, in the X., E. and D. Philosophical Magazine for 

 October, 1887, it was stated that a litre of hydrogen gas "at 0° 

 and 760 mm being assumed as the unit of volume for all species, 

 the weight of a litre of any other vapor or gas at the standard 

 temperature and pressure is its integral toeight. In like manner, 

 the integral weight of a liquid species is the weight of the same 

 volume at its boiling point under a pressure of 760 mm . . . . The 



Am. Jour. Sci— Third Series.— Yol. XXXV, No. 209.— May, 1888. 

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