Ch nd Physic 399 



iction. Hydrogen antimonide, on tbe other li:in«l, is at once 

 led by hydrogen Bulphide even when both air and I i sjc I > t. 

 absent. It' hydrogen antimonide be heated alone it begins to 

 Bociate at about 150°. This fact the author propose! to use 

 tbe detection of traces of hydrogen antimonide occurring 

 with hydrogen arsenide in hydrogen or other Fot this 



purpose, the mixture of gases is to be passed through a tube 

 about a meter long, heated to 208 -210 ; in a liquid bavins this 

 ling point. No arsenic whatever is deposited, while all the 

 antimony is thrown down. The mirror obtained may be exam- 

 ined in the usual way. — />> \ />>,/. Chem. Gtts., wii, 8202, Jan., 

 /. Chem. the., lviii, 209, Maroh, L890. <;. v. b. 



I ////'• Mass of Gold. — Mallet's final paper on the 

 raic mass of gold has been presented to tbe Royal Society. 

 The gold employed consisted (1) of material purified by himself, 

 the final red notion being effected with formic acid; (2) of mate- 

 rial furnished from the Philadelphia mint ; (3) of material ob- 

 tained from the New York assay office; and (4) of material sent 

 to him from the British mint. The results appear to have been 

 sibly the Bame by each method for all the gold used. Seven 

 of experiments are described. In the first, auric chloride 

 is precipitated with sulphurous acid and the gold weighed; 

 and, in the resulting solution, the chlorine was determined. In 

 the second, auric bromide was similarly treated. In the third, a 

 potassium auri-bromide solution was divided into two equal parts, 

 in one of which the gold was precipitated and weighed and in 

 the other the bromine was determined. In the fourth, tri-methyl- 

 ammonium auri-chloride was ignited and the metallic residue 

 weighed. In the fifth, an attempt was made to determine the 

 ratio between the weights of metallic gold and metallic silver 

 deposited by the passage of the same electric current through 

 their solutions. In the sixth, the electro-deposited gold was 

 Q pared with the hydrogen set tree by the same current. And 

 in the seventh, the gold was precipitated by metallic zinc, and 

 weighed, the hydrogen evolved by the excess of zinc being noted. 

 The mean of the first series is 106*722; 2d, 196-790; 3d, 190*775; 

 4th, 197-225; 5th, 196*823 ; 0th, 197'137; and 7th, 190*897; the 

 •ral mean being 196*910. — Phil. Trans., clxxx, A. 395, Xovem- 

 I 889. o. f. B. 



7. On Musical Tones by mean* of unlike formed Waves. — 

 Dr. KlJDOLPB ConiG shows, by a series of rotating wheels, in 

 which the intervals between the teeth are the same but of dif- 

 erent form, that the tones produced by the rotation of these 

 teeth against a suitable vibrator are musical ami do not obliterate 

 the fundamental tone produced by the main serrations of the 

 wheel, and can produce a musical note as long as the dissimilarity 

 in form does not change the amplitude of the fundamental wa\ 

 A number of diagrams of the seriated wheels accompany the 

 paper. — Wied. An,,. der Physik ",,,/ Chemie t No. 3, 1890, pp. 



-411. J. T. 



