THE FARMER'S MAGAZINE. 



211 



ASSIMILATION OV CARBON BY THE HELIANTHDS S. 



In deducting the weight of the seeds, 0.116, from the 

 weight of the dry plants, 1.1G8, wehave 1.052 for the or- 

 ganic matter developed in 89 days of a vegetation ac- 

 complished under the influence of 0.045 of nitrate of 

 potash absorbed by the heliauthuses, and including 

 0.0062 of azote assimilated. 



By admitting, according to previous analyses, into 

 the organic matter 0.40 of carbon, the plants would 

 have fixed 0.420 of it, proceeding from 1.544 of carbonic 

 acid, say 780 cubic centimetres of deg., and under the 

 barometrical pressure of m. 0.76. 



By day, and at a medium, the helianthuses have 

 therefore assimilated the carbon of ce. 8'75 of carbonic 

 acid gas. 



2nd Experiment : Helianthuses brought under the 

 influence of 0.16 of nitrate of potash. The soil was 

 formed of 



Grammes. 



Quartzose sand 400 00 



Fragmeuts of quartz 10000 



Phosphate of lime lO'O 



Nitrate 0-\6 



The flower-pot weighed .. .. 216 00 



71716 



The soil was steeped and washed with the distilled 

 water exempt from ammonia, and containing about one- 

 third of its volume of carbonic acid gas. The vegeta- 

 tion took place in the open air sheltered from the rain. 



On the 22nd June we planted two seeds weighing 

 together 0'116 grains, which should enclose 0'0033 

 of azote. On the 15th July, we counted four leaves 

 developed, and two budding on each plant. The coty- 

 ledons remained green till the 19 th of July. 



The 10th August there were many leaves, the oldest 

 of which were faded. 



The 20th September, each of the helianthuses bore 

 a fine flower of a deep yellow, having a corolla of 0'02m. 

 in diameter. Of fourteen leaves on the plants, eight 

 were faded. The largest of the leaves were 04 m. in 

 height by 0'02 m. in width. The height of the stalks 

 were 0-25 m. and 0'43. 



The roots were perfectly healthy, and were easily 

 disengaged from the sand. Dried in the stove, the plants 

 weighed 2'120 grammes. By analysis at one operation 

 they gave 00148 gr. of azote. 



THE DOSAGE OF NITRATE OF POTASH REMAINING IN 

 THE SOIL. 



In the water in which the seed and the flower-pot 

 pulverized were put in digestion, we dosed with 0'03725 

 grammes of nitric acid, the equivalent of 0*0697 gram- 

 mes of nitrate, enclosing of azote 0097 grammes. 



SUMMARY OF EXPERIMENTS. 



Grammes, 

 la the seeds, azote .. .. 0033 

 la 016 grams, of uitrate, azote 0'0222 



Grammes. 



Azote introduced .. 0-0255 0-0255 



Iq the plants, azote .. .. 0148 

 la the soil in the state of 



nitrate 00097 



Azote found 



00245 0-0245 



Difference .. .. 00010 



NITRATE ABSORBED BY THE PLANTS AND NITRATE 

 REMAINING IN THE SOIL. 



Grammes. 

 The nitrate of potash found in the soil was 0-0697 

 The nitrate of potash introduced .. 



1600 



Difference 



Of which the equivalent in azote is , , 



00903 

 0-0125 



If the nitrate expressed by this diflerence had been 

 absorbed, the helianthuses would have fixed 0-0125 

 grains of azote ; but there was not quite so much of 

 it, for 



Grammes. 

 The plants contained of azote .. .. 00148 

 Deducting the azote of the seeds .. 0.0033 



There will remain 00115 



for azote acquired, which was attributable to the nitrate 

 absorbed. 



As in the first experiment, there was one portion of 

 the nitrate which had not penetrated into the plants, 

 and which at the same time was not found in the soil. 

 It is this part of the nitrate which was transformed into 

 carbonate of potash. The water in which the soil and 

 the flower-pot had been placed to digest was very 

 slightly alkaline after concentration. 



DOSAGE OF POTASH ITST THE SOIL. 



In the water put in digestion over the soil we found 

 0.0043 gr. of potash, taking 0.0015 gr. of acid to con- 

 stitute 0.0028 gr. of nitrate. This salt belonging to 

 the soil, ought necessarily to be united to the nitrate 

 with which we dosed the acid. 



NITRATE OF POTASH ABSORBED BY THE PLANTS. 



Gr. 

 Nitrate corresponding with the potash found "I q QQ2g 



in the soil J 



Nitrate dosed in the soil 0.0697 



Nitrate not absorbed 0.0725 



Nitrate introduced into the soil 0.1600 



Nitrate of potash absorbed in the helianthusea. . 0.0875 

 Of which the equivalent in azote is 0.0125 



The azote fixed by the plants attributable to the uitrate 

 being 0.0115 gr., the two numbers differ only 6-lOths of 

 a milligramme. In the two experiments, we found in the 

 plants and in the soil almost the whole of the azote that 

 we had introduced by the seeds and by the nitrate of 

 potash given as manure. 



ASSIMILATION OP CARBON BY THE HELIANTHUSES. 



In eighty-nine days of vegetation, the vegetable 

 matter formed under the influence of 0.087 gr. of nitrate 

 of potash absorbed, weighed 2.104 gr., in which there 

 entered 0.848 gr. of carbon, derived from 3.109 gr. of 

 carbonic acid — say, in volume 1,566 centimetres of 

 degree, and under the barometrical pressure of 76 m. 

 Consequently, each day on an average, the helianthuses 

 assimilated the carbon of c. 17.6 of carbonic acid gas. 



In the following table are summaries of the results 

 obtained in the two experiments, showing that in that 

 circumstance the assimilation of the carbon has been 

 within a trifle in proportion with the azote of the 

 nitrate which has really intervened in the vegetation. 



These researches appear to me to have shown beyond 

 a doubt, that in the modification sometimes sustained in 

 the soil by the nitrate, its transformation into carbonate 

 of potash is due to a purely accidental cause — a re- 

 ductive action exercised by the dead vegetable matter. 



