Makch 15, 1907] 



SCIENCE 



403 



The Atomic Weight of Hydrogen: Wm. A. 



NOYES. 



This work, noAV in progress at the Bureau 

 of Standards, is in part a repetition of the 

 method used by the author some years ago, 

 when he obtained for the ratio H:0, 

 the values, 15.896 (H = l) or 1.00654 

 (0 = 16). When corrected for the gases 

 occluded in the copper oxide used as the 

 source of the oxygen, these values become 

 15.878 or 1.00765. In the recent work the 

 oxygen is weighed as copper oxide, the in- 

 crease in weight when the hydrogen is 

 passed into the tube is also determined 

 and, besides, the water is weighed sepa- 

 rately. In other determinations the hydro- 

 gen is first weighed absorbed in palladium, 

 and its weight checked by the increase in 

 weight of the copper oxide tube, as well 

 as by the weight of the water alone. The 

 mean of a number of determinations gives 

 a value which is somewhat higher than 

 Morley's on the oxygen basis. Other ex- 

 periments are in progress in which no 

 copper oxide is used, the oxygen being 

 passed directly into a tube containing 

 palladium saturated with hydrogen. In 

 this way as much as thirty-five to forty 

 grams of water can be formed in a single 

 determination, thus lowering the probable 

 error. 



The Selection of the Most Provable Value 

 for the Atomic Weight of an Element: 

 Wm. a. Noyes. 



A discussion of the principles which 

 should govern the selection of the atomic 

 weight of an element when a number of 

 workers have determined it in different 

 ways or by the same method. The later 

 determinations should usually have greater 

 weight than the older ones, and in many 

 cases the latter should no longer be 

 used in calculating the mean, especially 

 when sources of error overlooked by the 

 earlier investigators have been avoided in 

 the later work. 



The Separation of Calcium and Mag^we- 

 smm; Nicholas Knight. (By title.) 



Combinations of the Sesquioxides with the 



Acid Molyhdates: R. D. Hall. 



A study was made of the compounds 

 containing the various sesquioxides in com- 

 bination with the acid molybdates with a 

 view of determining whether they were 

 double molybdates or whether they were 

 derivatives of a complex inorganic acid. 



The methods employed were : (1) Prepa- 

 ration of other salts by double decomposi- 

 tion, (2) preparation of the free acid, 

 (3) dialysis of the alkali salts. All 

 favored the considering of these salts as 

 derivations of a complex inorganic acid. 

 The following nickel and cobalt derivations 

 were obtained: 



SKjO-NiO^-gMoOs and 3K,0-CoOa-9MoOs, 



analogous to the complex containing MnOj 

 in union with M0O3. 



The Direct Quantitative Analysis of Mix- 

 tures of Bromides with Chlorides: 

 Launcelot W. Andrews. 



On the Density Curve of Mixtures of 

 Bromine and Chlorine: Launcelot W. 

 Andrews. 



The Homogeneity of Tellurium: Victor 



Lenhek. 



In studying the action of tellurium and 

 tellurium dioxide toward various reagents 

 such as sulphur monochloride, phosphorus 

 oxychloride, antimony pentachloride, etc., 

 in addition to the formation of tellurium 

 tetrachloride or double chlorides, mother 

 liquors were obtained which were carefully 

 tested for tellurium and found by experi- 

 ment to contain tellurium with an atomic 

 weight of 127.5. Fractional precipitation 

 by means of ferrous salts from the chloride 

 solution gave the figure 127.55. By the 

 slow solution of tellurium in hydrochloric 

 acid, in presence of air, a fraction was 

 obtained, which gave 127.5 as the atomic 



