8 
N. C. AGRICULTURAL EXPERIMENT STATION. 
a bright-red color is formed where the two solutions meet, then nitric 
acid is present. This is a very delicate test, and, if properly handled, 
is very satisfactory. 
i Nitric acid, ( Quantitative ).—Use the Tiemann-Schultze method as 
described by Fresenius (Quantitative Chemical Analysis, p. 473). 
It is, however, more convenient to use a nitrometer according to 
Schiff, or some other convenient form, and the tobacco may be weighed 
and transferred directly to the flask, the amount taken to be varied 
according to the amount of nitric acid present. 
Total Nitrogen .—Determine by the Kjeldahl method of the Asso¬ 
ciation of Official Agricultural Chemists (Bulletin 31, Division of 
Chemistry, U. S. Department of Agriculture, p. 184). 
Ammonia .—Weigh out 10 grams of tobacco, and transfer to a 
Kjeldahl distillation llask. To this add 200 c. c ammonia-free water 
and 1 to 2 grams of recently ignited magnesia; distill this solution 
until the distillate is no longer alkaline, catching the distillate in 
very dilute sulphuric acid. Precipitate the nicotine in this solution 
with mereurio-potassic iodide. Filter, and wash thoroughly with 
water. Add sufficient, potassium sulphide to the fill rate and washings 
to piecipitate the excess of mercury ; then make alkaline with sodium 
hydrate, and distill off the ammonia, catching it in -A sulphuric acid. 
Determine the ammonia by titration. 
Albuminoids .—The nitrogenous substances termed albuminoids 
are found by multiplying by 6.25 the residue left on deducting from 
the total nitrogen, the nitrogen contained in the nicotine, ammonia 
and nitric acid. 
Ether Extract .—Place 2 grams of water-free tobacco in an extractor 
and extract for 24 hours with anhydrous ether. Evaporate off the 
ether, dry and weigh. This long continued extraction with ether is 
found to take out nearly all of what would be termed resinous or 
fatty substances. An additional extraction with absolute alcohol 
will remove what has not been removed by the ether. This residue 
must, how r ever, be washed with water, as the alcohol removes other 
substances besides the resins. A few experiments made by extract¬ 
ing with both ether and alcohol, washing the residues with water, 
drying, and weighing, gave nearly the same results as the ether 
extract alone without washing the residue. The extraction with 
alcohol being sotnewdiat difficult to manage, it was thought prefer¬ 
able, for the comparison in this bulletin, to extract with ether alone. 
Cellulose .—Proceed according to method for crude fiber, Bulletin 
31, U. S. Dept. Agr., Div. of Chem., p. 190. 
Pedic Acid .—Weigh out 2 grams tobacco and transfer to a filter, 
wash slowly with 80 per cent, alcohol, with which one-fourth the 
quantity of concentrated hydrochloric acid has been mixed. When 
the filtrate contains no further trace of lime, the acid is completely 
washed out with 80 per cent, alcohol. By this method the pectic 
