218 cook: leaves of amygdalaceae 



ammonia system extends to the formation of ammonobasic salts, 

 that is to say to the formation of compounds which are related to 

 ammonia as the ordinary aquobasic salts are related to water. 

 For example, mercuric chloride in the presence of liquid ammonia 

 undergoes ammonolysis in a manner represented by the reversi- 

 ble equation 



CI 

 HgCl 2 + 2NH 3 = Hg/ + NH4CI. 



X NH 2 



The formation of ammonium chloride 3 limits this ammonolytic 

 reaction just as the liberation of acid brings to an end the familiar 

 hydrolytic decomposition of salts of weak bases in water solutions. 

 In the longer paper the many points of resemblance between 

 water and ammonia are enumerated; a system of nomenclature 

 is outlined and an account is given of a considerable number of 

 typical reactions and new compounds of the ammonia system. 



BOTANY. — Jointed leaves of A mygdalaceae. O. F. Cook. Bureau 

 of Plant Industry. 



The leaves of the plum ; peach, and apricot have a joint at the 

 base, just above the insertion of the stipules, as do many legumi- 

 noseae. The basal section of the leaf, below the joint is in all 

 cases short, but is often as long as broad, and is the part to which 

 the stipules are attached. It does not fall off with the petiole 

 but remains alive and serves as a supplementary bud-scale. The 

 stipules are deciduous at an early stage, a fact which may have 

 allowed the persistance of the base of the leaf to remain over- 

 looked. 



It is not to be supposed, of course, that this specialization has 

 remained entirely unnoticed by preceding observers, but Sargent 

 and other authorities do not allude to it further than to state that 



3 Ammonium salts, whether of aquo acids or halogen acids, in solution in 

 liquid ammonia show certain truly acid properties. They bring about the rever- 

 sal of ammonolytic reactions, they dissolve many metallic oxides, they attack cer- 

 tain metals with the evolution of hydrogen and they discharge the red color of 

 alkaline phenolphthalein solutions. Their solutions in liquid ammonia are excel- 

 lent conductors of electricity. 



