1835.] Scientific Intelligence. 165 



insertion of the thermometers, the bulbs of two of which rested in 

 two cavities made in the standard bar. The vapour supplied from a 

 small vessel entered by a tube at one extremity and passed out freely 

 by the other end. 



The two micrometers were fixed by a vice to two solid isolated 

 blocks of stone placed at a convenient distance. Mr. Prinsep did not 

 confine his experiments to iron, but he took advantage of this oppor- 

 tunity to determine the dilatations of some other metals. The dila- 

 tation for the first thermic unit, that is, from 32° to 21 2°, he found :— 

 r Standard bar of 10 feet for the trigo- ^ 



T 1 nometrical survey I'00l213r , /xj^.oic 



^^°"- ^Bar of iron of Indian manufacture . 1-001210? '''''^^^ 



(Rod of iron 25 feet long 1-001256) 



Gold nearly pure 10 feet long 1*001438 



Silver containing -\ of alloy 10 feet long . . 1-001904 



Copper in plates re-roasted 1*001691 



Brass rod of 25 feet re-roasted 1*001906 



Lead tube 25 feet long 1 inch in diameter . . 1*002954* 



VIII. — Aldeide, and a New Acid. 



LiEBiG has discovered a new substance, which he terms Aldeide, its 

 composition being that of alcohol deprived of its water. It is obtained 

 by distilling alcohol or starch with anhydrous sulphuric acid. With 

 nitrate of silver a curious action takes place ; the metal is deposited 

 on the sides of the glass vessel in which the experiment is made, and 

 covers them with a coating of silver. 



The same chemist has also discovered a new acid, agreeing in its 

 composition, with formic acid, with the addition of 2 atoms of water. 

 It is obtained by drying the formate of lead, and decomposing it by a 

 current of sulphuretted hydrogen. 



It is a colourless liquid, congealing at 32^, and boiling at 212°. It 

 acts with prodigious energy on the animal textures, much more 

 powerfully than nitric acid. It destroys the skin like a hot iron ; 

 its smell is very strong when it contains an atom of water : it then 

 boils at 226°, and does not congeal at 32<^. — Journal de Chimie 

 Medic, i. 388, 2nd Ser. 



IX. — On the Evaporation of Charae. 



Those places in which Charae grow, are well known to fill the 

 surrounding air, in summer, with a very disagreeable odour. Pes- 

 sarini and Savi ascribe the cause to a volatile azotic principle, which 

 they term Puterin, They steeped a portion of these plants in water, 

 and allowed them to decay. A decomposition ensued, by which acetic 

 acid was formed, which dissolved the outer crust of carbonate of lime, 



* Journal of the Bengal ^Society, March, 1B33, and Bibliotheque Universelle, 

 February, 1835. 



