stated, arrowroot is free
from that peculiar odor due to potato starch. This may be most readily
developed by mixing the suspected sample with hot water; if it be
genuine arrowroot, the mixture is inodorous, if potato starch, the
smell of raw potatoes is immediately developed. If a mixture of
arrowroot and potato starch be minutely observed by means of a good
microscope, the grains of arrowroot may be readily detected; they are
very small and exceedingly regular in shape, whilst those of potato
starch are much larger, and very irregular in shape. But the most
convenient and delicate test of all, is that proposed by Dr.
Scharling, of Copenhagen. After mentioning the test by the microscope,
he goes on to state that he has obtained more favorable results by
employing diluted nitric acid; and that, if arrowroot or potato starch
be mixed with about two parts of concentrated nitric acid, both will
immediately assume a tough gelatinous state. This mass, when potato
starch is employed, is almost transparent, and when arrowroot is used,
is nearly opaque, as in the case above mentioned, in which
hydrochloric acid is substituted. A mixture of nitric acid and water,
however, operates very differently on these two kinds of starch. The
glutinous mass yielded by the potato starch, becomes in a very brief
period so tough that the pestle employed for stirring the mixture is
sufficiently agglutinated to the mortar, that the latter may be lifted
from the table by its means. Arrowroot, on the other hand, requires
from twenty-five to thirty minutes to acquire a like tenacity.

The _Lancet_ recently stated that, on a microscopical analysis of 50
samples of arrowroot, purchased indiscriminately of various London
tradesmen, 22 were found to be adulterated. In 16 cases this
adulteration consisted in the addition of a single inferior product
much cheaper in price, such as potato flour, sago meal, or tapioca
starch, while in other instances there was a combination of these
articles, potato flour being usually preponderant. Ten of the mixtures
contained scarcely a particle of the genuine Maranta or West India
arrowroot, for which they were sold. One consisted almost wholly of
sago meal; two of potato flour and sago meal; two of potato flour,
sago meal, and tapioca starch; one of tapioca starch; and four of
potato arrowroot, or starch entirely. The worst specimens were those
which were done up in canisters especially marked as "Genuine West
India