AEEOAYEOOT. 



349 



wat'^r) ; 1'48 of vegetable albumen; 0*6 of a gummy extract; 

 0 25 of cbloride of calcium ; 6 of insoluble fibrine ; and 65*6 of 

 water. 



Arrowi'oot is often adulterated in this country with potato 

 flour and other ingredients. 



Dr. Lankester asserts that the value of arrowroot starch, as an 

 article of diet, is not greater than that of potato starch, and that 

 the yield of starch is not greater from the arro^vroot than from 

 potatoes ; but this I must decidedly deny. Chemical analj/sis and 

 experience are proofs to the contrary. 



The analogy arro^vroot has to potato starch, has induced 

 many persons to adulterate the former substance with it ; and 

 not only has this been done, but I have known instances in 

 which potato starch alone has been sold for the genuine foreign 

 article. There is no harm in this, to a certain extent ; but it 

 certainly is a very great fraud upon the public (and one for 

 which the perpetrators ought to be most severely punished), to 

 sell so cheap an article at the same price as one which is com- 

 paratively costly. There is, moreover, in potato starch, a peculiar 

 taste, bringing to mind that of raw potatoes, from which the 

 genuine arrowroot is entirely free. This fraud, however, can be 

 readily detect(^d ; arrowroot is not quite so white as potato starch, 

 and its grains are smaller, and have a pearly and very brilliant 

 lustre ; and further, it always contains peculiar clotted masses, 

 more or less large, which have been formed by the adhesion of 

 a multitude of grains during the drying. These masses crush 

 very readily when pressed between the fingers, and as before 

 stated, arrowroot is free from that peculiar odor due to potato 

 starch. This may be most readily developed by mixing the sus- 

 pected 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 con- 

 venient and delicate test of all, is that proposed by Dr. Schar- 

 ling, of Copenhagen. After mentioning the test by the micro- 

 scope, 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 trans- 

 parent, 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 diiTerently 

 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 stirriug the mixture is sufficiently agglu- 

 tinated to the mortar, that the latter may be lifted from the 



