377 



Use of Paris-green. — Reports from different localities seem to iudi 

 cate that farmers are afraid to make use of Paris-green (arsenite of 

 copper,) for the destruction of the Colorado potato-beetle, thinking it 

 possible that the arsenic may be taken up by the tubers in sufdcient 

 quantity to become injurious to the health of consumers ; and the ques- 

 tion has arisen, " Is there any ground for this supposition." It is true 

 that arsenic has been taken up by cabbage in notable quantities, but 

 the conditions were highly favorable. It is also reasonable to suppose 

 that it would be assimilated by plants, from the fact that arsenic acid is 

 included in the same chemical classification as phosphoric acid, the two 

 compounds having many similar properties. But whether the former 

 may be substituted for the latter in the economy of plant-growth is a 

 point which has not yet, to our knowledge, been determined. We hope 

 to settle this point by the results of an investigation lately instituted 

 in our laboratory, which shall be published as soon as complete. In the 

 mean time, however, we think it will be safe to make applications of 

 Paris-green in the small quantities usually recommended, since the dan- 

 ger to the consumer from the small amount that can be taken up will 

 undoubtedly be very slight. 



Sugar contained in vine leaves. — Sometime ago M. Petit pub- 

 lished the fact that grape-vine leaves contain from 20 to 30 grams of 

 glucose and 13 to IG grams of acid, consisting principally of tartaric 

 acid in combination with potassa, per kilogram of leaves, and it ap- 

 peared to him that the sugar present was inverted sugar alone, without 

 admixture of cane sugar, but subsequent examination, by tests with. 

 Fehling's liquor, both before and after treatment with acid, and by 

 means of polarimetric tests, showed that cane sugar was present also. 

 He made two determinations of the amounts of each kind of sugar 

 I)resent after treatment with animal charcoal to remove the coloring 

 matter and taunin. 



In. the first, one kilogram of leaves gave — 



Cane sugar 9.20 grams. 



Glucose 2G.55 grams 



In the second, operating more rapidly, he obtained — 



Cane sugar 15.80 grams. 



Glucose 17.49 grams. 



He also found a mixture of cane sugar and glucose in the leaves of 

 cherry and i)each. One determination gave, per kilogram of leaves — 



Cane sugar 33 grams. 



Glucose , 12 grams. 



A SOLUBLE MODIFICATION OF STARCH. — After a Series of experi- 

 ments with this regard, M. Musculus has succeeded in obtaining a mod- 

 ification of starch, said to be soluble, and preserving at the same time 

 all the other x)roperties common to this substance. In order to obtain 

 this product, common starch is treated with strong acid, which is subse- 

 quently removed by repeated washings with cold water. A granular 

 body is left behind, which is insoluble in cold water, but completely sol- 

 uble in water heated to 50° C, and seems to be starch not aggregated 

 in grains or feculos, possessing all the other properties, especially the 

 same rotatory i)ower. 



The following table, prepared by Professor Freytag, showing the pro- 

 portions of proximate organic principles, as well as the percentages of 

 inorganic principles found in the ashes of several feeding-materials, has 

 been published in the general catalogue of the Royal Agricultural Mu- 

 seum in Berlin. The table will explain itself: 



