404 Scientific Intelligence. 



regard to chemical relations must be drawn with caution. In 

 view of these circumstances, Stromholm and Svedberg have 

 undertaken a study of the subject by the use of isomorphism. 

 As an example of the behavior of normal elements, the following 

 experiments were made : To equal portions of a warm saturated 

 solution of barium nitrate, equal amounts of dilute solutions of 

 silver, mercuric, lead and bismuth nitrates were added, and after 

 cooling it was found that the crystallized barium nitrate contained 

 neither silver, mercury nor bismuth, but it had taken up much 

 lead in solid solution. From a similar series of experiments with 

 potassium nitrate none of the above mentioned metals showed a 

 solubility in the solid phrase, while in the case of sodium nitrate 

 a considerable amount of silver and a little lead were found in 

 the crystals. The authors applied this method to a solution of 

 Rutherford's thorium-X, and found that this element is iso- 

 morphous with barium and lead, that it follows barium in its pre- 

 cipitations, and therefore belongs to the alkali-earth group of 

 metals. Similar experiments with thorium nitrate solutions gave 

 less definite results on account of the numerous radio-active bodies 

 present in such solutions, but it is the purpose of the authors to 

 extend their studies by this method to other series of radioactive 

 elements. — Zeitschr. anorgan. Chem., lxi, 338. h. l. w. 



3. The Hydrogen Silieides. — Lebeau, in a preliminary account 

 of his researches on the subject, shows that the hydrogen silieides, 

 produced by the action of hydrochloric acid upon magnesium 

 silicide, are more numerous than heretofore supposed. Besides 

 the two gaseous compounds SiH 4 and Si 2 H fi already known, it is 

 evident that a liquid silicide exists, and probably also one which 

 is solid at ordinary temperatures. Lebeau condensed a large 

 volume of the silieides by means of liquid air, then by allowing 

 the solid thus produced to attain ordinary temperature a com- 

 paratively small amount of hydrogen silicide, SiH 4 , free from 

 hydrogen, was given off, while a colorless liquid remained behind. 

 Upon fractionating this liquid there was obtained practically 

 pure Si 2 H 6 , which was found to boil at about — 1° C. The liquid 

 silicide w r as obtained only in small quantity and was not satisfac- 

 torily analyzed, but it appears to be silicoethylene, Si 2 H 4 . This 

 unsaturated compound is spontaneously inflammable with explo- 

 sive violence when exposed to the air, and it is probably the 

 vapor of this substance which gives spontaneous inflammability 

 to the two gaseous silieides when they are not perfectly pure. 

 The solid substance was observed as a small residue which 

 becomes brown upon exposure to the air and thus yields silicon. 

 — Bulletin, IV, v, 89. h. l. w. 



4. Determination of Boron. — Copaux and Boiteau have 

 studied several methods for the determination of this element, 

 including the extraction of boracic acid by means of ether, its 

 volatilization by means of methyl alcohol and its volumetric 

 determination by acidimetry in the presence of glycerine. They 

 find the latter method very satisfactory and particularly well 



