Chemistry and Physics. 321 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. The Decomposition of Silicates. — On account of the present 

 high price of platinum, and the available means of attaining high 

 temperatures, Walther Hempel recommends the use of barium 

 carbonate for the analytical decomposition of silicates, a process 

 proposed long ago by Deville. He states that the operation may 

 be carried out in a platinum crucible of 5 CC qapacity and 4 g. 

 weight. For the ignition he uses a Hempel furnace heated by a 

 gas blast-lamp in which a temperature of 1360° C. can be attained. 

 Since Berzelius showed that silicates less basic than orthosilicates 

 do not lose alkalies upon ignition, and since silicates as basic as 

 this are easily decomposed by hydrochloric acid, the method is 

 applicable to silicates containing alkalies, provided that not too 

 great a proportion of barium carbonate is employed. With 1 g. 

 of feldspar and 3 g. of barium carbonate the decomposition was 

 complete after heating for 15 minutes at the temperature men- 

 tioned ; the sintered mass was easily decomposed by dilute 

 hydrochloric acid and the platinum crucible was not attacked. 

 The same results were obtained with topaz and andalusite under 

 the same conditions. The great advantage of the method con- 

 sists in the fact that the barium is easily separated from the 

 other metals by means of sulphuric acid. — Zeitschr. f analyt. 

 Chem., lii, 86. h. l. w. 



2. The Presence of Manganese in Animals. — Bertrand and 

 Medigreceanu have examined many species of animals for man- 

 ganese, and find that it is distributed without exception in the 

 organism of all representatives of the animal kingdom. Among 

 the vertebrates, the mammals contain the least of the metals, 

 hardly more than a few hundredths of a milligram in 100 grams 

 of the total organism, although proportions five or ten times as 

 great occur among the birds, reptiles, batrachians and fishes. 

 Among the invertebrates the amount of manganese is generally 

 quite large, and it has been known previously that the mollusks 

 contain comparatively large amounts of the metal. It appears, 

 therefore, that the manganese plays an important part in the 

 vital processes of all animals. — Bulletin, xiii, 18. h. l. w. 



3. A General Method for the Preparation of the Ammonium 

 Salts of Organic Acids. — The usual method of preparing these 

 ammonium salts, which is by neutralizing the aqueous solution of 

 an acid with ammonia and evaporating to crystallization, gives 

 very unsatisfactory results owing to the hydrolytic action of 

 water upon these salts, and the literature shows that compara- 

 tively few of them have been made and analyzed. Keiser and 

 Mc Master have now devised a method for this purpose which 

 consists in dissolving the acid in ether or in a mixture of ether 



