Chemistry and Chemical Arts. 127 
of sugar in 2 parts of water, mingle the solution in a copper alem- 
bic with 24 to 3 parts of well pulverized peroxide of manganese. 
Heat the mixture to about 50° C, and add gradually, (taking care 
continually to agitate the whole with a wooden spatula,) three parts 
of concentrated sulphuric acid, which has been previously diluted 
with its weight of water. On the addition of the first third of the 
acid, a lively effervescence takes place, which will cause the vessel to 
overflow, unless it have fifteen times the capacity of the mixture em- 
ployed. Now put on the head of the alembic, and connect it with 
a refrigerating tube, in order to condense the acid vapors which are 
disengaged. Assoon as the motion produced by this reaction is over, 
add the other two thirds of the acid, agitate the whole, and distil to 
dryness. A limpid liquid of a penetrating odor is obtained, which 
is composed of a mixture of water, of formic acid, and of an oily sub- 
stance ; neutralize this with chalk, and evaporate it ina retort, if it 
is desired to collect the ether which passes with the water in which 
it is dissolved, and from which it is to be separated by means of the 
chloride of calcium. One pound of sugar furnishes enough formic 
acid to saturate five or six ounces of chalk. 
The formic acid is an excellent reagent for the reduction of the 
oxides and the chlorides of the noble metals ; and it separates, when 
in acid solutions, the noble metals from all the others. This reduc- 
tion and the separation take place instantly, or nearly so, in pour- 
ing into these solutions, heated almost to ebullition, a solution of an 
alkaline formiate. A brisk effervescence occurs in consequence 
of the transformation of the formic acid into carbonic, the metal is 
precipitated in a very fine powder, and so completely, that there 
does not remain a trace of it in the liquid. By collecting the car- 
bonic acid gas, and measuring its volume, the quantity of the noble 
metal present, however small, may be ascertained very exactly. In 
the cold, formic acid does not disturb the proto-nitrate of mercury ; 
but when heated to ebullition, the mercury is precipitated in the me- 
tallic state, while acetic acid forms with it a deposit of acetate in 
brilliant scales ; this property is peculiar in distinguishing the acids 
apart. Nevertheless the best reagent for formic acid is the acetate 
of lead; the formate of lead is white and crystalline, slightly solu- 
ble in water, and insoluble in alcohol. 
M. Goset has made the following very interesting researches 
respecting this acid. The solutions of gold, platinum and palla- 
dium are not decomposed by it when free, even though heated to 
