CHEMISTRY. 



109 



richer in nitrogen than the rest of the plant, 

 particularly in those experiments which showed 

 an increase of nitrogen. But this observation 

 can not be used to support the hypothesis ac- 

 cording to which the presence of nodosities or 

 microbes inhabiting the same should be the ex- 

 clusive cause of the assimilation of nitrogen, 

 because the increase of nitrogen was noticeable 

 in the soil as well as in the plants, and because 

 the gain of nitrogen by enrichment of the soil 

 was obtained in the culture of plants which did 

 not possess nodosities on the roots ; and the pure 

 culture proved the identity of micro-organisms 

 of the soil in which the lupines grew with those 

 occurring in the nodosities of the root of the 

 plant. The author therefore answers the ques- 

 tion of the intervention of nitrogen in plant 

 growth in the affirmative. 



The earlier results obtained at Rothamsted, as 

 well as those of Boussingault, respecting the 

 sources of the nitrogen of vegetation under con- 

 ditions in which the action of electricity and of 

 microbes was excluded led Messrs. Gilbert and 

 Lawes to conclude that the higher chlorophyl- 

 lous plants have not the power of taking up 

 nitrogen by their leaves or otherwise ; and that 

 atmospheric nitrogen is not a source of nitrogen 

 in the case of gramineous, cruciferous, chenopo- 

 diaceous. or solaneous crops, but that there was 

 not sufficient evidence to account for the whole 

 of the nitrogen taken up by leguminous plants. 

 Of the recent researches, those of Hellriegel and 

 Wilfarth, first published in 1886, were the most 

 conclusive. They tend to show that free nitro- 

 gen is fixed under the influence of a microbe- 

 seeding of the soil, with a resultant formation 

 of nodules on the roots. Experiments by the 

 authors in the seasons of 1888-'89, with several 

 species of leguminous plants, confirmed these 

 conclusions. Concurrently with the experiments 

 made at Rothamsted, M. Breal, of the Museum 

 d'Histoire Naturelle, in Paris, made various ex- 

 periments with similar results. Hellriegel agrees 

 with the authors that the leguminoscv utilize soil 

 nitrogen. He considers that the soil would be 

 drawn upon first, and that this source is supple- 

 mented by the elementary nitrogen of the air, 

 brought into combination by means of the or- 

 ganisms ; he also considers that there would be 

 more or less fixation, even with a soil rich in 

 nitrogen. On the other hand, Vines found that 

 the formation of tubercles, and presumably also 

 the fixation of free nitrogen, is much reduced, or 

 even stopped altogether, by the application of 

 much nitrogen to the soil ; and the Rothamsted 

 experiments indicate that with a rich garden 

 soil there are fewer nodules formed than with a 

 sand containing but little nitrogen, and seeded 

 with soil organisms. If subsequent experiments 

 should show this to be the case, the amount of 

 nitrogen of a crop derived from the air and the 

 amount derived from a soil would vary very 

 much according to circumstances ; fixation 

 would take place most freely in the case of a 

 sandy or poor and porous soil, and less in a 

 richer soil. On the whole, the evidence at com- 

 mand points to the conclusion that in the case 

 of most, if not all our leguminous crops, more 

 or less of their nitrogen is due to fixation under 

 the conditions suggested. 



The product which is designated in fodder 



analysis as ether extract is very crude, being 

 mixed with extraneous impurities which the 

 chemist has been much embarrassed to get rid 

 of. H. J. Patterson has successfully used animal 

 charcoal to obviate this difficulty, and has ob- 

 tained as products pure fats, and' in many cases 

 nearly pure vegetable oil. In filling the perco- 

 lator tube for the execution of his process, he has 

 first placed in it animal charcoal ; on top of this 

 a plug of cotton ; then the substance to be ex- 

 tracted; and finally another plug of cotton. The 

 cotton serves to make a more uniform stream of 

 ether over the substance, and keeps the latter 

 from crawling up the sides of the percolator. 

 The plug between the substance and the char- 

 coal will prevent any of the fat coming in con- 

 tact with the charcoal before it is thoroughly 

 in solution. In other respects Mr. Patterson's 

 method is like that of the Association of Official 

 Agricultural Chemists. The following points 

 are claimed in favor of the use of animal char- 

 coal: 1. That the product obtained is nearly 

 pure fat or vegetable oil; 2. That it gives a 

 more correct idea of the physical nature of the 

 fats from various substances; 3. That slight 

 quantities of water that may exist in the sub- 

 stance and pass out with the extract will be re- 

 moved by the charcoal ; 4. That soluble acids of 

 the plant, or acids which may be formed during 

 distillation, will be partially, if not wholly, re- 

 moved by the animal charcoal ; and 5. That the 

 animal charcoal will partially obviate, if not 

 wholly remove, the difficulty of change in the 

 amount of ether extract (which generally in- 

 creases) with the aging of the sample. 



The richness of the truffle in phosphoric acid, 

 lime, and magnesia, according to M. Ad. Chatin, 

 is remarkable in comparison with the poverty of 

 the soils. Six elements nitrogen, phosphorus, 

 potassa, lime, iron, and sulphur appear charac- 

 teristic of the truffle. The author concludes 

 that the nitrogen is derived in great part from 

 the air confined in the soil. Phosphoric acid 

 forms a mean of more than 50 per cent, of the 

 ash of the truffle, and it is closely followed by 

 potassa. Lime forms from 7 to 8 per cent, of 

 the ash, whether the earth contains 50 per cent. 

 of calcareous matter or hardly 1 per cent. The 

 proportion of iron oxide is about 5 per cent. 

 Soda is present to about 1 per cent., and rises in 

 some cases to 6 per cent. Magnesia rises and 

 falls along with the soda. Manganese, chlorine, 

 and iodine are present in all truffles. 



The results of an investigation of the saccha- 

 rine substance of the sweet potato by W. E. Stone 

 show that it exists chiefly, if not entirely, in the 

 form of sucrose. The quantitative determina- 

 tions showed from 1^ to 2 half per cent, of 

 sucrose in the fresh potatoes. The temperature 

 of cooking (baking) inverts the sucrose, and con- 

 verts more or less of the starch into a soluble 

 form. 



Miscellaneous. In the spontaneous combus- 

 tion of coal the carbon, hydrocarbons, and pyrites 

 all the constituents, in fact, except minerals 

 other than pyrites are found by Mr. Vivian B. 

 Lewes to take a part. Carbon possesses to an 

 extraordinary degree the power of attracting 

 and absorbing gases upon its surface, which is 

 increased as its surface is increased by division. 

 The absorption, at first purely mechanical, event- 



