292 Notice of some Recent 



Mode of measuring high temperatures. — Lampadius, after 

 endeavouring to point out the deficiencies in the modes 

 which we already possess of ascertaining the melting points 

 of those substance which require a high temperature for 

 fusion, recommends his Photoscope for this purpose, which 

 measures the light at different temperatures, such as dark 

 red, cherry-red, red heat, light red, white heat and dazzling 

 white heat. He gives, however, no description of his in- 

 strument, hut refers to his Beitr'dgen zur Atmosphdrologie.* 



CHEMISTRY. 



I. Solidification of carbonic acid. — Thiloriet has suc- 

 ceeded in reducing this gas to a solid state, by exposing it 

 to a temperature of 148° F. (?) Even when exposed to the 

 air, it remains in this state for a short time. Its elastic 

 force appears to be deteriorated by being solidified, as in 

 this state it gradually dissipates. It may be also rendered 

 solid by suddenly raising it from a liquid to a gaseous state. 

 When a stream of the acid is directed into a small glass 

 phial, the latter is filled with a white powder. If a small 

 portion of the solid acid is placed in a stoppered vessel, it 

 soon fills the flask with a thick vapour, and the stopper is 

 forcibly expelled. — Gazette Medicale, Oct., 1835. 



II. Naphthaline and its compounds. — Naphthaline was pro- 

 cured by Laurent, by boiling coal-tar in the open air until 

 it was deprived of its water, and then distilling it in a 

 retort with a copper beak and a glass receiver. The first 

 product is a yellow substance which turns black in the air, 

 and deposits much naphthaline. The second contains more 

 naphthaline; the third is viscid, orange-coloured, and con- 

 tains much para-naphthaline. The last contains a substance 

 with the colour of realgar, which has not been examined. 

 The first oils produce the naphthaline. These are distilled 

 and purified by crystallization by means of alcohol. The 

 specific gravity of its vapour is 4-528 by experiment. 



Hence, we may consider its composition, 



10 atoms Carbon, . . 4-166 = 7-5 10 atoms 

 5 „ Hydrogen, . -347 = -625 5 „ 



4-514 8-125 

 It is, therefore, a bi-penta-carbydrogen or C 10 H 5 . 



* Journal fiir praktische Chemie, iv. 181. 



