647 



1 mm.j, not even when the heating was continned for 48 hours. 



On the contrary, the dilatometer having l)een kept at 15° during 

 a month, tlie change was: 



At 101°.8 in 2 hours, +74 nnii.; i.e. +37 mm. per hour 



„ 100.9 „ IV, „ +20 „ ; „ +15 „ „ „ 

 „ 100.2 „ 12 „ —89 „ ; „ - 77, „ „ „ 



From these data one might conchide that there exists a transition 

 point in the neighbourhood of 101° which is in perfect agreement 

 with our density determinations (§ 4 — G). 



10. Guided by the experience gained in the case of cadmium and 

 copper ^), we now carried out some experiments with antimony 

 whose previous thermal historj^ had been changed between wide limits. 



After having Ivept the dilatometer for 50 minutes at 'J 50°, the 

 meniscus fell during a certain time at the constant temperature of 

 96°. 0; after this it became stationary and then began to rise. From 

 these observations one would conchide tliat there is a transition 

 point below 96°. and that, in consequence of the heating at 150°, 

 the transition temperature had thus been lowered. This experiment 

 proves, that at 96°. there are present at the same time more than 

 two modiücations. 



11. The dilatometer was now kept at 225° for 12 hours. After 

 this there occurred at 94^6 (at constant temperature) a marked fall 

 in the oil level (569 mm. within 48 hours), while in the experiment 

 described in § 10 there took place a rise of the meniscus at the 

 same temperature. 



12. The phenomena described above show that metallic antimony, 

 such as we have known it hitherto, is also a metastable system 

 which consists of more than two allotropic forms. 



We hope shortly to report on the modifications Which play a 

 role here. 



Utrecht, April J 914. van 't Eo¥¥-Laboratory. 



Chemistry. — "The Coloration o/ some derivatives of Picrylme^ 

 thylaniide ivith alkalies". By Prof. A. P. N. Franchimont and 

 H. J. Backer. 



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



In a previous communication {Rec. trav. chim. 1913, 32, 325 ; Ahstr. 

 Chem. Soc. 1914, ii. 84) we described the spectrographic investigation 

 of the coloration which picrylalkylnitramines undergo by alkalies. It 

 was shown, that the absorption spectrum of picrylmethylnitramine 



CgH, (NO.J5 N Me (NO,) after addition of alkali gets a certain ana- 



1) Proceedings 17, 54, 60 (1914). 



43 

 Proceedings Royal Acad. Amsterdam. Vol. XVU. 



