106 



CHEMISTRY. 



decomposes water at the ordinary tempera- 

 tures, combines with hydrogen under the in- 

 fluence of diffused light, and eliminates bro- 

 mine and iodine from their compounds ; it 

 unites with boron, silicium, and all the metals 

 of the first five groups. 



The Composition of Organic, Compounds. 

 Mitscherlich (Pogg. Annalen, April, 1867) de- 

 scribes a new method of determining the com- 

 position of organic compounds. He determines 

 hydrogen and oxygen in an organic compound 

 by heating it to redness in a current of chlorine, 

 when the oxygen unites with the carbon in the 

 substance, or that which has been added to it, 

 while the hydrogen combines with the chlorine 

 to make hydrochloric acid. The hydrogen 

 is obtained by weighing the latter, and the 

 oxygen is found from the carbonic oxide and 

 carbonic acid formed. He determines carbon, 

 chlorine, bromine, iodine, sulphur, and nitro- 

 gen by a single analysis; his process being 

 to volatilize the bodies under examination in a 

 current of hydrogen, and then burn the hydro- 

 gen along with the substances volatilized in pure 

 oxygen in a special apparatus. The water 

 formed is removed, and the other products 

 (with the exception of nitrogen, which is de- 

 termined by volume) are collected separately 

 in weighed apparatus. The author claims for 

 this method the advantages of ease, rapidity, 

 and freedom from the sources of error to which 

 other methods are liable. 



Chemistry and Vegetation. M. Carey Lea 

 contributes to the American Journal of Science, 

 March, 1867, an account of experiments made 

 by him to determine how far the germination 

 of seeds and subsequent vegetation of plants 

 would be controlled or influenced by the action 

 of acid, alkaline, and neutral bodies in solution 

 in the water with which the seeds were moist- 

 ened. The experiments were made by tying 

 pieces of very thin muslin over glass vessels 

 filled so full that the muslin dipped into the 

 liquid. Grains of wheat were placed on this 

 muslin, an equal number (twenty perfect grains) 

 on each. The capacity of each glass was twelve 

 and a half ounces, and the water was replaced 

 as fast as it evaporated. There was added, re- 

 spectively to each, as follows : 



1. 1 drop sulphuric acid. 



2. 2 drops nitric acid. 



3. 3 drops hydrochloric acid. 



4. 5 grains bicarbonate of potash. 



5. 5 grains dry carbonate of soda. 



6. 10 drops of rather weak liquid ammonia. 



7. 5 grains bromide of ammonium. 



8. A pair of zinc and copper plates, connected 



above the surface by a wire, and plunged in 

 plain water. 



9. Same, acidulated with three drops of hydro- 



chloric acid. 



10. Plain water for 'comparison. 



11. 5 grains sulphite of soda. 



12. 5 grains chlorate of potash. 



The following table shows the results at the 

 end of seven days, when the experiments were 

 discontinued : 



Total Results at the End, of Seven Days. 



A second set of trials was made, in which a 

 number of other substances were experimented 

 on, and at the same time sulphuric acid was 

 added in much smaller quantity, and sulphite 

 of soda in much larger. Capacity of the vessel 

 as before, twelve and a half ounces. 



1. Plain water. 



2. Cane-sugar, thirty grains. 



3. Gum, thirty grains. 



4. Glycerine, one fluid drachm. 



5. Sulphuric acid, one quarter drop. 



6. Citric acid, five grains. 



7. Sulphite of soda, twenty grains. 



8. Permanganate of potash, two grains. 



9. ^Nitrate of ammonia, twenty grains. 



At the end of thirteen days, during which 

 the weather was very cold (December 10th to 

 December 23d), the following was the condition 

 of affairs: 



Nos. 2 and 4 were as far advanced as No. 1, 

 but no further. In No. 3 fewer seeds germi- 

 nated than in either of the foregoing, but the 

 most advanced plants were fully one-half higher 

 than any in 1, 2, or 4. Nos. 7 and 9 grew 

 somewhat in advance of those in plain water, 

 but not very much. In No. 6 a large number 

 germinated and appeared healthy, but they did 

 not obtain one-fourth the height of those in 

 No. 1, and they formed no roots at all. In No. 

 5 the plants were more advanced than in the 

 citric acid, and had healthy roots extending 

 down into the liquid. In No. 8 the results 

 resembled those in No. 6. 



Some of the above sets of seeds were allowed 

 to vegetate a month, and the following effects 

 were noted : The plants which grew in the ves- 

 sels containing solutions of cane-sugar, gum, 

 and glycerine, grew as fast and flourished as 

 well as those in plain water, but it could not 

 be said that they presented any superiority to 

 those. But while the roots of the plants iu 

 plain water, in gum, and in glycerine reached to 

 the very bottom of the vessel, becoming four to 

 five inches long, those in the cane-sugar did not 

 exceed one inch in length, just dropping below 

 the surface of the water, which had become 

 lowered by spontaneous evaporation, and this, 

 although the plants were as high as in the others 

 just mentioned, viz. : six to eight inches, and as 

 numerous and healthy in every respect. 



The Proportion of Carbonic Acid in Differ- 



