146 



CHEMISTRY. 



barley, rice, and buckwheat have also yielded 

 considerable quantities of it. A little of it may 

 be found in the potato, and more in the beet, 

 the carrot, beans, peas, asparagus (principally 

 in the green part), sorrel, wild chiccory, let- 

 tuce, parsley, and in many fruits. It occurs in 

 large proportions in cacao and the coffees, and 

 in tea there are five grains of the metal to one 

 kilogramme of the leaves. Tobacco is quite 

 rich in it, as are also a variety of other plants, 

 including some forage and some medicinal 

 plants. 



Prof. F. H. Storer, of the Bussey Institution, 

 has made analyses of the leaves of the yellow 

 or curled dock (Bumex crispus), and of the 

 sprouts of the common milk-weed (Asclepias 

 cornuti), plants which are sometimes cooked 

 and eaten as greens, for the purpose of ascer- 

 taining their food-value. The dock-leaves were 

 taken when the tufts had attained a length of 

 about a foot and a half, and before any flower- 

 stocks had begun to appear. Of the milk- 

 weed, sprouts and shoots from four to twelve 

 inches long were cut off just below the sur- 

 face of the ground at about the same time, or 

 in the latter part of May. Analyses were made 

 of specimens of either kind dried, both in the 

 air and at 110 0. The analyses of the dock 

 gave the ratio of albuminoids to carbohydrates 

 as 1 : 2 ; those of the milk- weed as 1 : 1-6. Thus 

 both plants are shown to be highly nitrogenous 

 when young, and to compare favorably in com- 

 position with other weeds used as food, the 

 analyses of which have given good results. 



From analyses of ninety-two specimens of 

 wheat and straw ashes, the whole history of 

 each of which was known, Messrs. Lawes and 

 Gilbert conclude that there is, on the whole, 

 great uniformity in the mineral composition of 

 the grain, under different conditions of ma- 

 nuring, provided only it is perfectly and nor- 

 mally ripened. The influence of season pro- 

 duces a much wider range in the mineral con- 

 stituents of the grain than the manuring. This, 

 however, is not the case with the straw, as it 

 appeared that the amount of mineral and ash 

 constituents found in it have a direct connec- 

 tion with the amount available in the soil. 



Experiments made by Prof. Gilbert and Dr. 

 W. J. Russell show the existence of a close 

 connection between the formation of chloro- 

 phyl and the amount of nitrogen assimilated 

 by plants. The amount of carbon assimilated 

 is not, however, in proportion to the chloro- 

 phyl formed, unless a sufficiency of mineral 

 substances required by the plants is available. 

 In cases where nitrogenous and mineral ma- 

 nures were applied, a lower proportion of nitro- 

 gen assimilated, and chlorophyl formed over 

 a given area was observed ; and this is no doubt 

 due to the greater assimilation of carbon and 

 consequent greater formation of non-nitroge- 

 nous substances. But the amount of nitrogen 

 assimilated and chlorophyl formed were as 

 great, if not greater, in the latter case than in 

 the former. 



Berthelot and Andre", of Meudon, France, 

 have conducted a series of investigations on 

 the existence of nitrates in plants, the results 

 of which they have published in four memoirs. 

 They found that, of the plants they examined, 

 Borrago officinalis and the Amarantacecz con- 

 tained most nitrates ; that those salts are most 

 abundant in the stems, and next in the roots ; 

 that they increase from germination till just 

 before flowering, and then diminish, but in- 

 crease again after the reproductive function is 

 completed, and even after the death of the 

 plant. Four sources are suggested as possible 

 origins of nitrate : the fertilizers used ; the soil; 

 the nitric acid of the atmosphere; and forma- 

 tion in the plant itself. Analysis of the soil 

 showed that the earth over a hectare, to the 

 depth of 0*325 of a metre, contained less than 

 half the quantity of nitrate contained in the 

 Borrago grown en its surface, and less than 

 one sixth of that in the gigantic amaranth. 

 Direct experiment also showed that the ni- 

 trates in the soil did not perceptibly increase 

 during the growth of nitrates in the plant; 

 and that even when they were washed out of 

 the soil by the rain the quantity in the plant 

 remained sensibly the same. As to the atmos- 

 phere, analyses at the Montsouris Observatory 

 showed that the nitrate in the rain which fell 

 during the season amounted upon a hectare to 

 4-4 kilogrammes only, or hardly one twentieth 

 of the quantity in the soil. The authors there- 

 fore conclude that the formation of nitrates 

 in plants is an established fact, and seems to 

 result from the special action of a more gen- 

 eral function of the cellules, the function 

 which gives rise to oxidations; that is to say, 

 the same function which produces carbonic 

 acid and carbonates, oxalic, tartaric, citric, 

 malic, and other peroxygenized acids. 



Prof. J. H. Gilbert records, as the result of 

 comparable experiments at Rothamsted with 

 the same crop, that depth of green color by 

 no means implies a finally greater amount of 

 carbon assimilation; while it had previously 

 been experimentally proved there that the 

 deeper color, was associated with relatively 

 higher percentage of nitrogen in the dry or 

 solid substance of the herbage ; and this obvi- 

 ously means a lower relation of carbon to nitro- 

 gen. Further experiments were instituted in 

 co-operation with Dr. W. J. Russell, who un- 

 dertook to make comparative determinations 

 of the amounts of chlorophyl in parallel speci- 

 mens, while Prof. Gilbert and his associates 

 were to determine the percentages of dry mat- 

 ter and nitrogen. The facts were brought out 

 in these experiments that the separated legu- 

 minous herbage of hay contains a much higher 

 percentage of nitrogen in its dried substance 

 than the separated gramineous herbage ; and 

 that, with the much higher percentage of ni- 

 trogen in the leguminous herbage, there was 

 also a much higher proportion of chlorophyl. 

 Under comparable conditions, the leguminoCB 

 eventually maintain a much higher relation of 



