20 Profs. W. B..and R. FE. Rogers on the 
impurities ; second, from the much larger amount of formic acid 
obtained by it from an equal weight of the oxidizing material, 
sulphuric acid and starch or sugar; and third, from ake ease rate 
which the action is controlled. 
According to Liebig, (Chem. coane Pp. 567,) 10 satan of scat; 
37 parts of peroxide of manganese, and 30 parts of sulphuric 
acid, yield 3:35 parts of an acid liquid, * which 100 grains sat- 
urate 15 grains. of carbonate of soda. This corresponds to 7:18 
parts of liquid such as we obtain.. We have thus by the old pro- 
cess 7:18 parts of liquid of equal acidity with our product, while 
the aggregate weight of the starch, sulphuric acid, and peroxide 
of manganese is 77. By our process we have about 1800 grains 
of a similar acid from 2100 grains of sugar, bichromate of potassa 
and sulphuric acid. In other words, by the new process, we pro- 
cure about nine times as much formic acid from the same weight 
of the three reacting materials, as by that hitherto in use. 
Il. On the preparation of Aldehyde and Acetic Aout . the use 
of the nie aati “i Pouiissa. 
In the weonseipidiiiceiitl by: Liebig, sGtacin: eis) pp. 378, Jani 
which is the one hitherto generally used for preparing aldehyde 
in the regular way, the product is obtained from the reaction of 
peroxide of manganese and sulphuric acid upon dilute alcohol. 
This operation furnishes a liquid which is so weak in aldehyde, 
and so mixed with water and formic ethers, and as we have found 
with acetic acid also, as to present the characteristic reactions only 
in a feeble degree, and to require two rectifications over chloride 
of calcium, before it can be used in forming the ewe aE or 
aldehydite of ammonia. 
In the course of some experiments upon the reactions of. ie 
chromate of potassa and sulphuric acid upon alcohol, we have 
been led to a process which affords a larger and much purer pro- 
. duct, and which is entirely. under the control of the operator: 
The distinctive features of this method are the substitution of 
bichromate of potassa for the peroxide of manganese, and the 
peculiar mode of bringing the reacting materials together. In 
the use of the bichromate we have since found that we were an- 
ticipated by Profi Kane, who, at page 922 of his Elements of 
Chemistry, recommends it as a means of obtaining a purer pro- 
