12 
FROZEN POTATOES. 
In a memoir laid some months ago before the Institute 
of France, M. Payen, the celebrated chemist, made some 
valuable observations upon the subject of frozen Potatoes, 
which are usually considered useless, and are consequently 
thrown away. As it appears from his investigations that 
Potatoes are in no material degree injured by frost, but that 
they are as nutritious after being frozen as before, and in 
some respects more useful as food, I translate literally the 
report made to the Institute by Messrs. Turpin and Dutrochet 
upon a subject of such vast importance to mankind ; pre- 
mising only that it is the starch of the Potatoe which gives 
it its nutritive qualities. r 
Frozen potatoes are usually, after being thawed, thrown 
away as altogether unfit for food, even for cattle; they are 
found to have acquired an acrid taste, and the makers of 
starch know by experience that they do not yield more than 
3 or 4 per cent. of starch instead of 16 or 17 per cent. which 
they furnish in their uninjured state. M. Payen endeavoured 
to ascertain the cause of this difference. It might be 
supposed that the effect of a thaw would be to alter the 
amylaceous matter, in consequence of which it might become 
soluble. But M. Payen satisfied himself, by exact and 
positive experiments, that thawed potatoes and those in the 
natural state each contain exactly the same proportion of 
soluble and insoluble matter. This being so, there ought to 
be as much starch in a potatoe after being frozen as before ; 
and consequently M. Payen suspected that the loss of starch 
experienced by the starch-maker in frozen potatoes was 
owing to some mechanical obstacle which opposes the ex- 
traction and separation of this substance. This idea was 
confirmed by a microscopical examination of the tissue of 
the potatoe, thawed and rasped down. We know that the 
starch is contained in the cells or vesicles of parenchyma, of 
which the potatoe is composed ; the rasp, by tearing open 
the cells, sets the starch at liberty. It is obvious that if the 
rasp produces such an effect, the cells must be fixed firmly in 
the tissue ; otherwise they would be only torn asunder by 
the teeth of the rasp, and the starch which they contain 
could not get out of the cells. Now M. Payen discovered 
that this actually happens when a potatoe is successively 
