CHEMISTRY. 



147 





nitrogen to carbon than the graminece; in 

 other words, in their case carbon is not assimi- 

 lated in so large a proportion to the nitrogen 

 taken up. Wheat-plants, manured with ammo- 

 nium salts alone, show a much higher percent- 

 age of nitrogen than those manured with the 

 same amount of ammonium salts with mineral 

 in addition. The result was exactly similar in 

 the case of barley. It is evident that the 

 chlorophyl formation has a close connection 

 with the amount of nitrogen assimilated, but 

 that the carbon assimilation is not in propor- 

 tion to the chlorophyl formed, if there be a 

 relative deficiency of the necessary mineral 

 constituents available. No doubt there had 

 been as much, or more, of both nitrogen as- 

 similated and chlorophyl formed over a given 

 area, where the mineral as well as the nitroge- 

 nous manure had been applied ; but the lower 

 proportion of these substances in the dry matter 

 was due to the greater assimilation of carbon, 

 and consequent greater formation of non-ni- 

 trogenous substances. These results of experi- 

 ments in the field are perfectly consistent with 

 those obtained by vegetable physiologists in the 

 laboratory, who have found that the presence 

 of certain mineral or ash constituents, and es- 

 pecially of potassium, is essential to the assimi- 

 lation of carbon. 



From experiments reported by MM. Dehe"- 

 rain and Maquenne, on the absorption of car- 

 bonic acid by leaves, it appears that the pro- 

 portion of pure carbonic acid absorbed under 

 atmospheric pressure varies with the quantity 

 of water contained in the leaves. 



The results of Aime" Girard's investigations 

 of the alimentary value of the several tissues 

 of which the wheat-grain is composed go to 

 show that while a considerable proportion of 

 the seed-coats is digestible by man, the pro- 

 portion thus utilized, when calculated upon the 

 whole grain, is very small, and the quality of 

 the bread is impaired by the presence of those 

 substances. This is particularly the case with 

 raised bread. According to Mege-Mouries, the 

 envelope contains a soluble ferment resembling 

 diastase, which, during the raising process, 

 in addition converts starch into sugar and 

 diminishes the elasticity of the gluten, thereby 

 tending to make the bread heavy, while it also 

 imparts a brown color to it. Bread made with 

 baking-powder would naturally escape these 

 effects to a large extent. It is certain that 

 wholesome, palatable bread, which many per- 

 sons may prefer for dietetic reasons, may be 

 made from whole wheat-flour. But, from an 

 economical point of view, such flour can hardly 

 claim any great advantages, so long as nearly 

 every one can command a mixed diet, and 

 the bran can be 'profitably utilized as cattle- 

 food. 



Miscellaneous. All compounds of arsenic are 

 known to be toxic except the so-called ar- 

 senic-methyl bodies, or cacodyl compounds. 

 Concerning these the testimony has been con- 

 flicting. The principal experiments on the 



subject have been made with cacodylic acid 

 (CH 8 )a As OOH, a compound which contains 

 34'35 per cent, of metallic arsenic, equivalent 

 to 71'4 per cent, of arsenious oxide. Bunseu 

 and Kurschner found it not poisonous. Schmidt 

 and Chomse reached a similar conclusion. Le- 

 bahn experimented on rabbits, all of which 

 died, and concluded that cacodylic acid does 

 possess poisonous properties, and that its toxic 

 symptoms are like those of ordinary arsenical 

 poisoning. John Marshall and Walter D. 

 Green, of the University of Pennsylvania, 

 made a series of experiments upon dogs in the 

 fall of 1885 with what they had ascertained 

 by severe tests to be perfectly pure cacodylic 

 acid. The most marked effects and symptoms 

 following the administration of the drug were : 

 nervous symptoms, with vomiting, purging, and 

 slowing of respiration, due to spinal irritation 

 and slight paralysis ; decided weakness in the 

 hind extremities ; and a peculiar condition of 

 somnolence resembling hemiplegia. The symp- 

 toms as a whole were nearly analogous with 

 those produced by arsenious oxide, but the 

 results were not fatal. The experimenters 

 reached the conclusion that cacodylic acid is 

 not a poisonous substance in the general ac- 

 ceptation of the word poison. 



In illustration of the volatility of mercury, 

 Berthelot remarks that, in his laboratory is a 

 mercurial trough, and some eight feet from it 

 a glass case containing a bottle of iodine. After 

 some years, he noticed that the neck of this 

 bottle above its junction with the stopper was 

 covered with red mercuric iodide. 



W. Engling has found that ammonium oxa- 

 late when added to milk does not precipitate 

 its calcium salts ; but that if, after the addi- 

 tion of the oxalate, calcium chloride be added, 

 the ,casein is separated and carries calcium 

 oxalate along with it. He infers from these 

 facts that the calcium of milk "is in definite 

 organic combination with the casein, and this 

 combination must first be destroyed before 

 calcium can be separated as oxalate. The cal- 

 cium albumin ates in milk resemble basic salts, 

 and are readily decomposable by acetic, lactic, 

 and tartaric acids." W. Mattieu Williams sug- 

 gests that this view of the chemical condition 

 of the calcium of milk has considerable physio- 

 logical and practical interest, in the light it 

 may throw upon the manner in which the 

 bone-material of infants and the young of ani- 

 mals is separated from the milk upon which 

 they are fed. Combinations of bases with 

 mineral acids are rarely if ever broken up in 

 the animal body for assimilation, and it is at 

 least doubtful whether such compounds are 

 appropriated in their combined state for or- 

 ganic construction and renewal. " But a loose 

 compound of calcium with casein is just the 

 sort of material which can be, and is, sub- 

 jected to chemico-vital metamorphosis. If it 

 can be shown that the phosphoric acid of the 

 milk is also combined with an easily dissocia- 

 ble organic base or bases, we have the condi- 



