SCIENTIFIC SUMMAET. 
241 
2 Drecipitate, by pouriug an excess of ]\Ietliylic alcoliol upon either of the other 
thallic alcohols. The three coini^onnds burn with a bright green flame, 
lea^ung a residue yrliich consists of black oxide, containing small globules of 
the metal. They are soluble in the alcohols from which they are derived, 
and in ether and cliloroform, but are readily deconi 2 )osed by water or even 
by the moisture nsnally present in the atmosphere : in such cases the alcohol 
is disengaged, and hydrated oxide of thallinm is deposited. — Vide 
Caviptes Bendus, Nov. 7th. 
The Decomposition of Formic Acid. — M. Berthelot continues his researches 
upon this matter, and states that he causes the organic acid to sj)lit into 
either carbonic oxide and water or carbonic acid and hydrogen, the 
difference de 2 )ending aj)]3arently upon the coni 2 )leteness of the process. 
If only a j)ortion of the formic acid be decomposed, then the 2 >roducts are 
carbonic oxide and water ; but if the whole of the acid is broken u^), then 
there result carbonic acid and hydrogen. In concluding his 2 )a]Der M. Ber- 
thelot draws these two conclusions : — 
“ 1st. Formic acid in vapoiu when submitted to an elevated temperature 
is deconi 2 )osed with evolution of intense heat. 
“ 2nd. Formic in vapour, when acted on by a high temjDerature, becomes 
converted (according to the experimenter’s will) into either carbonic oxide 
and water, or carbonic acid and hydrogen.” — Vide Comptes Bendus, Nov.. 
* 14th and 21st. 
The Detection of Nitro-Benzol in Oil of Bitter Almonds. — M. Dragendorjff 
asserts that nitro-benzol is very easily detected by acting on the adulterated 
oil with sodium, in the j)resence of alcohol. This metal in contact with 2 >ure 
oil of bitter almonds disengages gas, which is increased by the addition of 
alcohol, and white “flocks” are formed. Nitro-benzol, under the same circum- 
stances, with alcohol, becomes dee^D brown or black and viscid. In testing 
the adulterated oil, take ten or fifteen drops of it, add four or five drops of 
alcohol and a piece of sodium ; a brown dej)osit, approaching black in pro- 
2 >ortion to the amount of nitro-benzol present, occurs. This reaction is 
instantaneous, and when from 30 to 50 per cent, of nitro-benzol is present, 
a thick broAvn liquid is produced by the above application in less than a 
minute. — Vide Journal de Pharmacie and Chemical News, Nov. 12th. 
Changes of Temperature produced by Mixing various Liquids. — ^At the 
sitting of the French Academy, which took place on the 24th October last, 
Messrs. Bussy and Buignet presented a paper detailing the conclusions at 
which they arrived from a number of experiments made uj)on mixtures of 
different liquids. The compounds which they esjDecially investigated were 
ether, alcohol, bisulphide of carbon, acetic acid, chloroform, essence of tnr- 
j)entine, and distilled water. From these researches they conclude that : — 
1st. When two liquids, capable of mutual solution in aU proportions, are 
mixed together, a change of tem 2 )eratnre is always observed ; the thermometer 
either rises or falls. 
2nd. The effect observed is always the result of one or two causes actmg 
in ojDposite directions. The one — affinity— acting upon the heterogeneous 
molecules, tends to 2 )i’ocluce heat. The other, acting upon homogeneous 
molecules, tends to 2 )roduce cold. 
3rd. When the two liquids have a feeble affinity, the effects of diffusion 
YOL. lY. NO. XI Y. E 
