769 



The recent experiments of Haselhoff and GosseP leave no doubt as to 

 the poisonous effect of Rhodanammonium, the decomposition of which even 

 in sandy soil does not take place so easily as earlier examples seemed to 

 prove. Even a very small amount, such as 0.0025 per cent., produces a con- 

 siderable delay in germination and since the purified gas phosphate still 

 contains 0.76 per cent. Rhodanammonium the above named scientists could 

 not recommend it at all as a fertilizer, even with the difficult solubility of 

 phosphoric acid. 



4: Ammonium sulfate. In connection with this, a case of injury 

 due to ammonium sulfate should be mentioned here, which was previously 

 unknown. A car full of plants (Azaleas), when opened, showed that the 

 leaves had been partly blackened as if from ammonia fumes. Subsequent 

 investigations showed that the car had been used previously for the trans- 

 portation of ammonia sulfate. Experiments made immediately proved that 

 free ammonia developed in the presence of calcium. In the same way, fresh 

 ammonium sulfate which has not been sufficiently dried and neutralized 

 can develop ammonia and as in the case described in the section on am- 

 monium fumes this can adhere to the walls and subsequently act injuriously. 



5 : Calcium nitrid. This recent product of our fertilizer industry still 

 gives rise to repeated complaints. Calcium carbid used primarily in the pro- 

 duction of the very bright illuminating gas, acetylene, and obtained from the 

 interaction of lime and carbon in an electric oven is exposed in hermetically 

 sealed iron mufflers to the action of nitrogen with intense heat and then 

 furnishes the calcium nitrid as an unpurified calcium cyanamid with possibly 

 20 to 24 per cent, nitrogen. This calcium nitrogen, or calcium cyanamid, has 

 the peculiarity of giving off all its nitrogen in the form of ammonia when 

 heated with water under pressure. By passing the ammonia through sulfuric 

 acid it is possible to produce the valuable fertilizer, ammonium sulfate. 

 The "calcium nitrid" (CaCN^) contains about 20 to 21 per cent, nitrogen; 

 40 to 42 per cent, calcium and 17 to 18 per cent, carbon, besides impurities of 

 silicic acid, clay, traces of phosphoric acid, etc. By removing the calcium, 

 there are produced Cyanamid (CN.NH.) and the homologous Dicyandiamid 

 [CN,(NH,)2]- 



The calcium, present in the calcium nitrogen, which acts as a strong 

 alkali, is partly free and partly combined in the form of calcium cyanamid. 

 For this reason it should not be brought into contact with supersulfat 

 because the phosphoric acid would then be made insoluble. The rules for its 

 use are approximately as follows :- — The quantity used per hektar according 

 to the constitution of the field, is 150 to 300 kg. corresponding to 30 to 60 kg. 

 nitrogen. To avoid the loss in dust the calcium nitrid is mixed with twice 

 the amount of dry earth. This should be spread i to 2 weeks before the 



1 Haselfhoff, E., u. Gossel, F. Versuche tiber die Schadlichkeit des Rhodanam- 

 iiioniums fur das Pflanzenwachstum. Zeitschr. f. Pflanzenkrankh. 1904, p. 1. Bibli- 

 ography here g-iven. 



2 Brahm, Der Kalkstickstoff und seine Verwendung- in Gartenbau und Land- 

 wirtschaft. Gartenflora, Berlin, 1906, Part 10. 



