ltering off the
active ultra-violet rays. How far some such method as this might prove
successful I cannot say, but since we cannot keep our dyed textile
materials in a vacuum, as Chevreul did, nor is it desirable to
impregnate them with mastic varnish for the purpose of excluding air
and moisture, as Mr. Laurie proposes, in order to preserve the colors
of oil paintings, it is perhaps well to bear in mind the principle
here alluded to as a possible solution of the difficulty.

I have dwelt rather long on this important question of the action of
light on dyed colors, but I have done so because I thought it would
most interest you. With the remaining portions of my subject I must be
more brief.

(_To be continued._)

* * * * *

To introduce free fat acids from an oil, it must be decomposed. This
may be done by the use of lead oxide and water or by analogous
processes. To clarify an oil, expose to the sun in leaden trays. Often
washing with water will answer the purpose.

* * * * *

COMPOSITION OF WHEAT GRAIN AND ITS PRODUCTS IN THE MILL.

Probably the most striking difference in the average mineral
composition of the grain of wheat is the very much lower proportion of
phosphoric acid, and of magnesia also, in the dry substance of the
best matured grain; and it is now known that these characteristics
point to a less proportion of bran to flour, or, in other words, of a
greater accumulation of starch in the process of ripening, and
consequently of a whiter and better quality of bakers' flour. The
study of the chemical composition of wheat and its products in the
mill, therefore, and of the amount of fertilizing matters (nitrogen,
phosphoric acid and potash) removed from the soil by the crop, becomes
of direct interest not only to the producer from whose soil these
ingredients are removed, but to the consumer of the byproducts as
well, who desires to know what proportion of these elements of
fertility he is returning to his own soil in the different products he
may use as animal food. It is desirable also to determine what is the
average composition of wheats and the flour made from them, in order
to see in what direction efforts should be turned, by the selection of
seed wheats, to improve the present varieties for the production of
the best quality of flour. This can only be done after we determine
what variation there is for different years d