540 Scientific Intelligence. 



samples of water were used, and different kinds of glass were 

 employed for the sealed tubes. All , the tubes froze between 

 — 2° C. and —1-6° C. ; the mean of the experiments being — 1-86° 

 C, and that for the purest water with a conductivity of 1*1 X 10~ 6 

 being —1-9° C. The authors conclude tna»t — 1*9° is the tem- 

 perature at which under atmospheric pressure water freezes 

 spontaneously, i. e., in the absence of particles of ice, and they 

 call attention to the remarkable fact that this is the temperature 

 at which super-cooled water possesses a maximum refractive 

 index according to the observations of, Pulfrich. The effect of 

 friction was also studied by introducing glass, garnet, galena, or 

 lead into the tubes; this caused the water to freeze at —0*4 C. — 

 Ghem. News, xciv, 89. h. l. w. 



3. Preparation of Fused Molybdenum. — Molten molybdenum 

 was first prepared by Moissan by the use of the electric furnace. 

 It has been made also by several experimenters by the "thermite " 

 process, consisting in allowing the trioxide to react with finely 

 divided metallic aluminium. The volatility of molybdenum tri- 

 oxide, however, made this process unsatisfactory. Biltz and 

 Gartner have modified the u thermite" process by using the 

 non-volatile dioxide in place of the trioxide". To prepare the 

 dioxide the trioxide is heated to moderate redness in a glass tube 

 in a current of hydrogen gas. The "thermite" process then 

 works well, the authors having obtained a yield of 93 per cent of 

 the theoretical, and a product which contained over 98 per cent 

 of the metal. — jBerichte, xxxix, 3370. h. l. w. 



4. Potassium-lead Chlorides. — By fusing mixtures of the two 

 chlorides in varying proportions, determining the temperatures at 

 which crystals were deposited by cooling, and investigating the 

 products thus obtained, Lorenz and Ruckstuhl have found that 

 three double salts are produced from the fused mass. They are 

 represented by the formulae 2PbCI 2 .KCl, PbCl a .2KCl, and PbCl„. 

 4KC1. It is interesting to notice that these three types of double 

 lead salts — in one case only with water of crystallization— are 

 known among: the double halides of the alkali metals and lead 

 which crystallize from aqueous solutions, and that still another 

 type corresponding to the 1 : 1 ratio, for example, CsCl.PbCl a , is 

 also known. — Zeitschr. anorgan. Chem., li, 11. h. l. w. 



5. Ammonia from the Mecent Eruption of -Vesuvius. — Stok- 

 lasa has examined volcanic exhalations and many eruptive 

 products of eruption of April, 19.06, and has found ammonia 

 always present in them. He draws the conclusion that the 

 ammonia has its origin in the chemical actions which take place 

 in the hot lava, possibly from the presence of silicon nitride or 

 other nitrides. He considers the view of the mineralogists, that 

 the sublimations of ammonia are caused by the combustion of 

 vegetation, to be entirely incorrect. — JBerichte, xxxix, 3530. 



H. L. W. 



6. Beitraege zur Chemischen PJiysiologie and Pathologie, 

 herausgegeben von F. Hofmeister. VIII Band. 1906, Braun- 

 schweig (Fr. Vieweg und Sohn). — This volume is quite equal to 



