On thr Trcatmonf of Decayed Potatoes, ^v. 
557 
be freed from the disease in an easy manner, it would be in the 
highest degree culpable not to preserve it. It happens fortu- 
nately that the diseased part of the potato, when the tuber has not 
become much dried, is almost wholly soluble in water ; or at least, 
which practically amounts to the same thing, that the parts which 
do not dissolve are so light that they may easily be removed from 
the sound matter by pouring off the water. This being the case, 
we can obtain almost all the really valuable portion of a diseased 
potato by simply grating it down and stirring it up with water. 
The diseased portions dissolve in the water, and the pulp and 
starch fall down together. The red-coloured water must now be 
drawn off, and fresh water again put on ; this washing, repeated 
twice or at most three times, gives a mixture of pulp and starch, 
which when dried and ground offers a meal similar in colour to 
oatmeal. Professor Liebig recommends a very good plan when 
oil of vitriol can easily be obtained : it consists in slicing the 
potato and immersing the slices in water containing enough sul- 
phuric acid to render it very distinctly sour to the taste. The 
slices must afterwards be washed with frequent water, as the acid 
adheres very obstinately. The addition of acid to water is useful, 
especially when the disease has been much dried in. In most 
instances, even when water alone is used, it is not necessary to 
grate down the potato as we do in making starch ; it suffices to 
cut it into pieces, in the same way as we slice turnips or potatoes 
for giving to cattle. The only evil attending the process now 
described is the removal of the soluble albumen. As the albu- 
men is carried off in the water employed in washing, one lialf of 
the really nutritious matter of the potato thus disappears : but 
when we pursue the common method of making starch and 
neglecting the pulp, the ichole of the nutritious matter is removed, 
and we obtain only starch, which by itself is not fitted to support 
animal life. 
Other processes for converting diseased potatoes into whole- 
some food have been recommended ; and as one of them, viz. 
steaming, has received the powerful support of Dr. Buckland, I 
shall allude to it in the first place. It consists in passing steam 
through a vessel containing potatoes until they are rendered soft, 
after which the softened mass is to be rammed down into air- 
tight casks, which are to be covered with melted fat. The 
potatoes must previously be pared, the diseased parts being cut 
out, and these are to be preserved separately. A plan very similar 
to this is that proposed originally by Parmenlier, of boiling 
potatoes after being peeled, crushing down the boiled potatoes 
and drying the mass. 
It is quite undoubted that these plans yield a very excellent 
article of food, and they ought to be followed when circumstances 
2 p 2 
