167 
CHEMICAL MEMORANDA. 
By Wm. McMurrTRI£, CHEMIST. 
PROXIMATE ANALYSIS.—Proximate analysis may be classed among the 
most difficult processes of analytical chemistry. It not only requires 
patience, but often yields results which fail to produce the satisfaction 
desired. To reduce the difficulties to a certain extent, and to devise a 
method which will yield satisfactory results, and insure economy in time 
and expense, has been in part the object of the work in the laboratory 
during the past two months, and, as was stated in our last month’s report, 
we shall now proceed to the publication of our method of analysis. 
Since the separation of the several proximate principles depends upon 
the action of different solvents, the work of devising a method of effeet- 
ing it obviously consists in the selection of such as are best suited to 
the purpose, as well as the best means for applying them. In the selec- 
tion of solvents, attention must be paid to their wetting powers as well » 
as their power of solution. Thus ether will dissolve a larger proportion 
of oil than bisulphide of carbon, but ‘the latter being more penetrating 
will extract the oil from the meal more readily than the former. We 
have therefore chosen as solvents to be used in the following method, 
_bisulphide of carbon, alcohol of 85 per cent., water, and dilute acid and 
alkaline solutions. 
The best mode of extraction of the different principles with solvents is 
by percolation, and this operation may be very materially aided by the 
use of the Bunsen pump. In order that the residues may be dried and 
weighed without destroying the filter, Munroe’s porous earthenware cones, 
14$ inches in diameter, are used, and these are fitted into glass funnels 
by means of a ring of rubber tubing. 
The material having been carefully and finely pulverized, take two 
samples of 2.5 to 3 grammes each, heat at 130° C. until constant weight 
is obtained, in order to determine the moisture. Then place them upon 
the porous cones and determine the oil by extraction-with bisulphide of 
carbon. The residue after this extraction, as after each succeeding one, 
must be dried at 130° C. until constant weight is obtained. The oil 
having been removed, the two samples are treated for zein, sugar, and 
gum as follows: Let the cones be numbered respectively land 2. Treat 
the contents of No. 1 with alcohol of 85 per cent., which will remove the 
zein and sugar. After having dried and weighed it, treat the residue 
with water to remove the gum; dry and weigh. Treat the contents of 
cone No. 2 with water to remove the gum and sugar; dry and weigh. 
The amounts of zein, gum, and sugar may now be calculated as follows: 
Treatment of No. 2 with water = gum and sugar. 
Second treatment of No. 1= gum. 
First treatment of No. 1 = zein and sugar. 
Gum + sugar — gum = sugar. 
Zein + sugar — sugar = zein. 
The substance having been treated as above is transferred from the 
cone to a beaker 12 inches high and 3 inches in diameter, and boiled for two 
hours with 200 ¢.c. of water containing 0.5 per cent. of sulphuric acid. 
As the water evaporates it must be supplied. After boiling, the beaker 
is filled with hot distilled water, the residue allowed to settle, and the 
clear supernatant fluid is drawn off as completely as possible, by means 
