3 1 4 Intelligence and Miscellaneous Articles. 



•s 



acid, very pungent vapours of formic acid are given out ; the head 

 of the alembic must then be put on and communication made with 

 the refrigeratory to condense the vapours. As soon as the action of 

 the acid is over, the remaining two thirds of the acid are put into the 

 boiler j the mixture is to be well agitated, and distillation carried on al- 

 most to dryness, in order that all the formic acid produced may pass in- 

 to the receiver. A limpid liquid acid is obtained which has apenetrating 

 odour j it is composed of water, formic acid, and an aethereal matter. 

 It is to be neutralized with a carbonate, (chalk answers best,) and 

 evaporated ; this last operation ought to be performed in a retort 

 with a receiver adapted to it : if it be wished to separate the aethereal 

 matter, which evaporates with the water and remains dissolved in it, 

 it may be effected by distilling the aqueous product from chloride of 

 calcium. A pound of sugar furnishes formic acid enough to saturate 

 5 or 6 ounces of carbonate of lime. The residue is protosulphate of 

 manganese, artificial malic acid, and a kind of extractive matter. 

 The sulphate of manganese may be employed in dyeing instead of 

 sulphate of iron, to deoxidize indigo. If concentrated formic acid 

 or formic aether be required, the formic acid produced from the sugar 

 is to be saturated with carbonate of soda j the solution is to be eva- 

 porated to dryness, and 7 parts of the dry salt, reduced to powder, are 

 to be distilled either with 10 parts of sulphuric acid and 4 of water, 

 or with a mixture of 10 parts of concentrated sulphuric acid, and 6 

 parts of perfectly rectified spirits of wine. The formic aether produced 

 in the latter case ought to be agitated, if it is acid, with a little cal- 

 cined magnesia j it may be separated from alcohol by agitating it 

 with a little water, and it is deprived of the water by distilling it with 

 chloride of calcium. 



"The properties of this aether are well known ; one of the most re- 

 markable is, that when put in contact with water, the bodies com- 

 posing it are reproduced, namely, alcohol and formic acid. When it 

 is mixed with dilute alcohol, it suffers no alteration j hence a mixture 

 of 1 part of formic aether and 3 parts of rectified spirit may be pre- 

 served, (spiritus Jbrmico-aithereus)." — Ann. de Chim. et de Phys. 

 torn. lii. p. 105. 



EXPERIMENTS ON THE ACTION OF LIME ON CERTAIN SOLUTIONS 

 OF CARBONATE OF POTASH. BY HENRY HOUGH WATSON. 



Among the Miscellaneous Articles in the London and Edinburgh 

 Philosophical Magazine and Journal of Science for September 1832, 

 will be found an extract from Ann. de Chim. et de Phys. xlix. p. 142, 

 in which M. Liebig states that "if one part of carbonate of potash be 

 dissolved in four parts of water, and the solution be boiled with slaked 

 lime, the potash does not lose the smallest quantity of carbonic acid ; 

 it does not become caustic, even though lime be added to any extent, 

 or however long the boiling may be continued." Now, as the first 

 part of this statement is considerably at variance with the one which 

 I should give, as founded on the result of my own inquiries, without 

 further premise I venture to lay before the readers of the Philosophi- 

 cal Magazine a few experiments lately made on the same subject. 



