108 HOW CEOPS GROW. 



According to Haschke, (Jour, fur Pr. Ch&amp;gt; 79, p. 148,) 

 the crystalloid aleurone that is abundant in the Brazil 

 nut, is a compound of casein with some acid of unknown 

 composition. This aleurone may be dissolved in water, 

 and recovered in its original form on evaporation. 



Kubel s analysis of aleurone, prepared from the Brazil 

 nut by Hartig, gave its content of nitrogen 9.46 per cent. 

 Aleurone from the yellow lupin yielded him 9.26 per cent. 

 Since pure casein has 16 to 18 per cent of nitrogen, the 

 aleurone contained about 52 to 59 per cent of albuminoids. 



Estimation of the Albuminoids. The quantitative sep 

 aration of these bodies is a matter of groat difficulty and 

 uncertainty. For most purposes their collective quantity 

 in any organic substance may be calculated with sufficient 

 accuracy from its content of nitrogen. All the albumin 

 oids contain, on the average, about J. 6 per cent^ of nitrogen. 

 This divided into 100 gives a quotient of 6.25. If, now, 

 the percentage of nitrogen that exists in a given plant be 

 multiplied by 6.25, the product will represent its percent 

 age of albuminoids, it being assumed that all the nitrogen 

 of the plant exists in this form, which in most cases is prac 

 tically true. 



Frtthling and Grouven have recently investigated the 

 condition of the nitrogen of various plants, and have found 

 that nitric acid, (N a O B ,) which in the form of nitrate of 

 potash has long been known to occur in vegetation, is 

 present in but trifling quantity in most agricultural plants. 

 In mature clover, esparsette, lucern, wheat, rye, oats, bar 

 ley, the pea, and the lentil, it did not exceed 2 parts in 

 10,000 of the air-dry plant. In maize, they found twice 

 this quantity ; in beet and potato tops alone of all the plants 

 examined was nitric acid present to the amount of four- 

 tenths of one per cent, ( Vs. St., IX, 153.) Salts of am 

 monia (N H a ) likewise often exist in plants, but as a rule 

 in quite inconsiderable quantities. 



