Reynolds — Action of Metameric Compounds on Plants. 613 



LXXXIII. 0:^ THE CoiEPAEATIVE EFFECTS OF TWO MeTAJEEEIC BoDLES ON" 



THE Growth of ISTicoTiijs^A loi^gifloea. By J. E:m:eesox Betnolds, 

 M.D., P.E..S., Professor of Chemistry, TlniTersity of Dublin. 



[Eead, April 10, 1882.] 



The study of the comparative action of metameric compounds on the 

 growth of plants seems to deserve more attention than it has yet 

 received from chemists and vegetable physiologists, and the aim of 

 the communication I now beg to lay before the Academy is to show 

 that well-marked differences in physiological activity can be detected 

 with the aid of plants, even in cases of metameric bodies of compara- 

 tively simple constitution. 



The bodies selected for experiment were ammonium sulphoeyanate 

 and its metamer thiocarbamide, or sulphurea. Both compounds are 

 rich in nitrogen, and therefore capable of supplying a highly impor- 

 tant element of plant food ; they are easily soluble in water, and, 

 consequently, admit of absorption thi'ough the roots of plants ; more- 

 over, their chemical relations have been carefully studied, and their 

 differences of structure are known, hence they seemed to be very 

 suitable for the class of work in which I proposed to employ them. 



The sulphoeyanate is a true ammonium salt of sulphocyanic acid, 

 and its composition is represented by the formula 



NH'4 CIS'S'. 



The metamer of this body, or thiocarbamide, I discovered in 1869, and 

 obtained in the following way : — 



The salt was melted, and the temperature of the Kquid raised to 

 170° C, when rearrangement of the components of the molecule took 

 place ; the mass, when cooled, extracted by water and crystallized, 

 afforded fine crystals of thiocarbamide. This body contains the 

 same elements as the sulphoeyanate, and in the same proportions, and 

 its molecular weight is the same ; but its relations and chemical struc- 

 ture are very different, as it is a feeble base, and destitute of saHne 

 characters, while its reactions are represented by the structural for- 

 mula — 



During the summer of 1881, I made several sets of experiments 

 with these bodies on selected groups of plants which are known to 

 afford special nitrogenised or sulphuretted products, when grown 

 under normal conditions. Some of the results obtained are suffi- 

 ciently definite to justify their publication, while others require repe- 



