1-4 BULLETIN 76, U. S. DEPARTMENT OF AGRICULTURE. 
and shows no lumps of gelatinized starch remaining, which should 
take a little over an hour. The flask is quickly cooled in running 
water until it can be comfortably handled, then a few drops of methyl 
orange are added, followed by concentrated ammonia to alkaline reac- 
tion. Next is added 800 c. c. of 95 per cent alcohol with thorough 
mixing, and after a few minutes standing to allow air bubbles to sepa- 
rate, the liquid is strained through moderately coarse muslin. The 
addition of this amount of alcohol is insufficient to permanently pre- 
cipitate any starch, but notably thins out the original aqueous solu- 
tion. Starch will separate some time after the solution has become 
cold, but with proper management ample time remains for the subse- 
quent necessary operations. The solution, still at 40° to 45° C, is 
run through a number of fine jets into 4,000 c. c. of 95 per cent alco- 
hol, under continuous stirring. The whole is left for at least 4S 
hours with an occasional thorough stirring, after which most of 
the supernatant alcohol is decanted, and the rest used to transfer the 
starch to a 2-quart narrow percolator provided with a filter plate 
which is covered with filter paper or cloth. Here it is i^ercolated 
with 95 per cent alcohol, being stirred up with a stick at intervals to 
prevent the formation of clumps or fissures, until the alcohol comes 
through of a specific gravity indicating a strength of 90 per cent. 
The starch is then transferred to a Buchner funnel, well drained with 
suction, and then spread out to dry in a moderately warm place. 
The starch so prepared is a fine white powder, more or less compacted 
to friable lumps, which completely disintegrate under slight pressure. 
A little of it thrown into cold water in less than a minute dissolves 
sufficiently to yield a good blue upon the addition of iodin and potas- 
sium iodid. Moistened with water or diluted alcohol it becomes 
gummy and dries out to a horny mass, difficultly soluble in cold water. 
The efficiency of the preparation therefore is dependent upon its 
fine state of subdivision, and care must be taken during the process not 
to expose it to air until after thorough digestion with alcohol of 90 per 
cent strength. It should be passed through a 60 or 80 mesh sieve 
and protected from moist air. 
The soluble starch may be thoroughly mixed with 10 times its 
weight of powdered sodium bicarbonate and the mixture divided into 
powders of about 0.6 gram, which may be packed in a paste- 
board box fitting into compartment B of the case. On the large 
scale, however, it is much better to make the mixture up into tablets. 1 
after the following formula: 
1 It is something of an art to make good tablets. Xo one should attempt it until thoroughly conversant 
with the principles of the process, and then only on a small scale until experience is gained. 
