12 
N. C. AGRICULTURAL EXPERIMENT STATION. 
Malic acid .—The alcohol is evaporated off from the last filtrate. 
When this has been completed the liquid is agitated with acetic acid 
in excess, and a sufficient amount of acetate of lead having been 
added, the whole is overflowed with 5 to 6 volumes of 80 per cent, 
alcohol, containing .005 parts acetic acid. The malate of lead sep¬ 
arates completely as neutral salt. After standing for 12 or 15 hours 
filter, wash, dry, weigh, ignite in a porcelain crucible, and weigh as 
oxide of lead. The loss of weight by ignition is the weight of 
the malic acid. The organic matter which is mingled with these 
precipitates is usually so small that it need not be considered. The 
phosphoric acid is precipitated as phosphate of lead, and comes 
down with the citrate of lead. This amounts to but a few milli¬ 
grams, and may be estimated by dissolving the lead oxide after igni- 
nition with acetic acid, and deducting what remains from the total 
weight. This method for extracting these acids, although not all 
that could be desired, gives fairly good results if carefully managed. 
It is more satisfactory than any other method that was tried. 
Crude ash .—Char 2 to 3 grams of substance at the lowest pos¬ 
sible red heat in a muffle, and burn until white, or when by further 
burning there appears to be no change in the appearance of the ash, 
taking care not to have heat enough to fuse it. 
Ash Analysis. 
The ash is burned in the same manner as for the determination 
of crude ash, thoroughly pulverized in an agate mortar, and pre¬ 
served in bottles fitted with rubber stoppers. 
Solutions .—One gram of ash is weighed into a 6 oz. beaker, and a 
little water added, covered with a watch glass, and HC1 added cau¬ 
tiously until effervescence ceases, then a few drops of HC1 added in 
excess, and the whole evaporated to dryness. The residue is then 
moistened with HC1, water added and heated on a water-bath for a 
few minutes, then filtered through a fared Gooch crucible. The 
residue (sand, silica and carbon) is dried, weighed and ignited. The 
loss is taken as carbon, and the remainder as sand and silica. The 
filtrate is made up to 200 c. c. and used in the following determinations: 
Sulphuric acid .—Fifty cubic centimeter of the filtrate is made up 
to 100 c. c. or more, heated to boiling, a boiling solution of barium 
chloride added, and heated until the supernated liquid is clear; 
then filtered, washed, dried, ignited, and weighed. The precipitate 
is barium sulphate, from which the SO 3 is calculated. 
Alkalies.— The filtrate from the above is heated to boiling, a slight 
excess of barium chloride is added drop by drop with constant stir¬ 
ring; without filtering, and in the same manner barium hydrate is 
added in slight excess. Heat, filter, and wash until precipitate is 
free of chlorides. Add to the filtrate 1 c. c. of ammonia, and then a 
saturated solution of ammonium carbonate until the excess of barium 
