58 Scientific Intelligence. 



between the atomic weights of the two kinds of iron, for the 

 average of eight determinations on the meteoric material was 

 55*832, while the outcome of the results of the other work was 

 55'838. — Jour. Amer. Chem. Soc, xxxiii, No. 3. h. l. w. 



3. The Compounds of Ammonia and Water. — The question of 

 the existence of the compound XH 4 OH in solutions of NH 3 in 

 water has attracted much attention in the past, but while the 

 theory of the existence of the hydroxide has been a plausible one, 

 it has been opposed by several investigators. Smits and Postma 

 have now shown from freezing-point determinations of mixtures 

 of XH 3 and H 2 that the compounds NH 3 .H 2 and 2NH 3 .H 2 0, 

 corresponding to NH 4 OH and (NH 4 ) 2 0, certainly exist, and that 

 these are the only compounds formed. They melt at about 

 — 77 : C. and —75" C. respectively, or a little below the melting 

 point of pure NH S , while there are eutectics between the two 

 compounds and between each of them and a constituent. The 

 existence of these compounds, although it gives no proof of their 

 chemical constitution, undoubtedly strengthens the hydroxyl and 

 oxide theory, for it shows that XH 4 can be regarded as combin- 

 ing with water in the same way that an alkali metal does, for 

 example, to produce KOH and K 2 0. It may be added that 

 Rnppert has obtained the same results by freezing-point deter- 

 minations as those that have been mentioned, but published them 

 somewhat later. — Zeitschr. anorgan. Chem., lxxi, 250. h. l. w. 



4. The Quantitative Determination of Fluorine as Calcium 

 Fluoride. — The usual method for carrying out this determina- 

 tion, following Berzelius, is to precipitate the calcium fluoride 

 together with calcium carbonate, and, after filtering and igniting 

 the mixture, to dissolve out the calcium carbonate with dilute 

 acetic acid and finally collect and weigh the fluoride. Staeck 

 and Thobin have made a modification of this method, which con- 

 sists in precipitating calcium fluoride in the presence of an exactly 

 known amount of an oxalate in a solution containing about two 

 cubic centimeters of free acetic acid. The amount of oxalate 

 should be about the same as that of the fluoride. The precipita- 

 tion is made in the hot solution by the addition of calcium chlo- 

 ride solution. The mixture, which filters as well as calcium 

 oxalate alone, is collected on asbestos, dried at 210° C, and 

 weighed. By deducting the known amount of calcium oxalate, 

 the weight of fluoride is found. From the results obtained by 

 the authors it appears that the method gives very satisfactory 

 results, and it is evidently a great improvement upon the old 

 method. — Zeitschr. analyt. Chem., li, 14. h. l. w. 



5. The Volumetric Determination of Antimony in Alloys. — 

 Dr. G. S. Jamiesox of the Sheffield Laboratory has applied 

 Andrews' iodate titration to this determination. The alloy, such 

 as hard lead or solder, is dissolved in concentrated sulphuric acid 

 by heating to boiling, the residue is treated with a mixture of 

 equal volumes of strong hydrochloric acid and water, the lead 

 sulphate is filtered off and washed with hydrochloric of the same 



