645 



Chemistry. — ''The Allotrop'/ of Antunony.'^ T. \\\ Prof. Ernst 

 Cohen and J. C. van den Bosch. 



(Communicated in the meeting of September 26, 1914). 



1. The following modifications of this metal were known hitherto: 



a. The so called uietalUc antimony, a bhiish-white solid witii 

 metallic lustre. It is very brittle at ordinary temperatnres and is 

 said to crystallize in the hexagonal system. Only this moditication 

 is found in natuie. 



b. Black antimony. This form has been prepared by Stock and 

 SiKBERT ^) in three different ways, the best method being by rapid 

 cooling of the vapour of ordinary metallic antimony. This black 

 modification is converted by heatnig into metallic antimony. Its colour 

 and density change slowly at 100'^; at 400^ the conversion occurs 

 instantly. This form seems to be metastable at ordinary temperatmes. 



c. Yellow antimony was first prepared by Stock and Guttm.vnn ^) 

 in the year 1904, by the interaction of antimony hydride (at — 90°) 

 with air, oxygen or chlorine. Even at — 50^ this form is meta- 

 stable : it is converted by heating into the black modification. 



d. Explosive Antimony. Ernst Cohen, Ringer, Strengers, and 

 Collins ^) proved that the explosion which occurs when this body 

 is pounded, pressed or scraped, is to be attributed to the transformation 

 of an allolropic form called by them ^-antimony, into the ordinary 

 modification (metallic antimony ; «-antimony). Hitherto no investigation 

 of the connexion between these different forms has been carried out 

 as it is very difficult to procure sufficiently large quantities of them. 



2. The investigations described below deal with the question 

 whether the metal known hitherlo as "metallic antimony" is to be 

 considered at ordinary temperatures and pressures as a metastable 

 system, as is the case with the metals we have already investigated. 

 Our experiments will prove that this \>> really the case. 



3. A kilogram of antimony (Kahlbaum — Berlin) which contained 

 some hundredths of a percent of impurity, was melted and poured 

 into a cylinder of asbestos pai)er, which was surrounded by a mixture 

 of alcohol and solid carbon dioxide. The chilled metal so obtained 

 was used in all experiments. 



4. It was powdered in a mortar. We determined its density at 

 25°. using two pycnometers as described by Johnston and Adams ^). 



ij Ber. d. d. chem. Ges. 38, 3887 (1906). 



2) Ber. d. d. chem. Ges. 37, 885 (1904). 



8) Zeitschr. f. physik. Chemie 47. 1 (1904V 50, 292 (1904); 52, 129 (190Ü). 



*) Journ. Am. Chem. Soc. 34, 563 (1912). 



