8 



atom of carbon is displaced by two atoms of nitrogen, and calcium 

 cyanamide (CaCN.2) is formed. This substance is also produced 

 when a mixture of lime or chalk and charcoal is heated to a 

 temperature of 2,000° C. in a current of air.* When pure, this 

 substance holds 35 per cent, of nitrogen, but in its crude com- 

 mercial form it contains only about 20 per cent. Treated with 

 acids, calcium cyanamide is changed into dicyandiamide, a sub- 

 stance holding nearly 67 percent, of nitrogen, but directly poison- 

 ous to plants. Or, if heated in superheated steam, calcium 

 cyanamide parts with all its nitrogen as ammonia, which, of course, 

 is easily brought into a portable form. 



But experiments conducted at Posen and Darmstadt during the 

 past three years, both in pots and in the open field, have shown 

 that calcium cyanamide itself is a useful nitrogenous manure, field 

 experiments giving results about 20 percent, below those obtained 

 by the use of an equal amount of nitrogen in the form of sulphate 

 of ammonia. In prepared soil in pots the results fully surpassed 

 those obtained both with nitrate of soda and sulphate of ammonia, 

 the less satisfactory yields obtained in the field being perhaps due 

 to the organic acids inducing the formation of a certain amount 

 of the poisonous dicyandiamide. 



So far as one may judge from the information available, it would 

 appear that agriculture will not have long to wait until it is placed 

 in the possession of new supplies of that most powerful agent of 

 production, nitrogen, and Sir William Crookes will see the fulfil- 

 ment of his prediction that " the future can take care of itself." 



Nitragiti. 



A few years ago much interest was excited in this and other 

 countries by the announcement that the scientific discoveries of 

 Hellriegel and Wilfarth had received commercial application, and 

 that the organisms of the nodules of the roots of Leguminosae 

 could be purchased in a form convenient for artificial inoculation. 

 The specific cultures placed upon the market were largely tested 

 practically and experimentally, but the results were such as to 

 convince even the patentees, Nobbe and Hiltner, that the problem 

 which promised so much for agriculture had not been satisfactorily 

 solved. Since that time however, investigators have not been idle, 

 and the present position of the subject is to be found in a recent 

 report by Hiltner and Stormer.f 



It was early recognised that the organisms (bacteria) which in- 

 habited the root-nodules of the various species of Leguminosae 

 were not all alike, and that, in fact, they showed marked physio- 

 logical if not morphological distinctions. Any particular species 

 of leguminous plant is found to resist more or less successfully the 

 attempt of these various organisms to effect an entrance into its 



* Bull. Imp. Inst. June 30th, ]90i. 



t" Bericht iiber oeue Untersucliungen iibei- die WurzelknoHchen derLeguniiuosen and 

 deren Errege'," Arheiten aits der Biol. Ahteil. Jiir Land-imd Forstwirtschaft am K- 

 Gesundyieitsamte, Band iii. Heft 3. 



