557 
of Edinburgh , Session 1868 - 69 . 
between the action of bases containing nitrogen as a triad and 
those in which that element is pentad. This result was obtained 
from an examination of the physiological action of substances 
having an unknown and complex constitution. It appeared to be 
necessary to institute a series of experiments with bodies having a 
simpler and fully known constitution. For this purpose, the salts 
of ammonia, tri-methylamine, and tetra-methyl-ammonium were 
selected. A comparison of the structural formulae of the hydro- 
chlorates of these bases shows that tri-methylamine stands in the 
same relation to the salts of tetra-methyl-ammonium as strychnia 
to the salts of methyl-strychnium. 
The iodide of tetra-methyl-ammonium was prepared by mixing 
iodide of methyl with an excess of ammonia dissolved in alcohol, 
and recrystallising the crystalline precipitate from hot water. 
From the iodide the hydrate was obtained by the action of oxide 
of silver; and by distilling the hydrate and conducting the vapours 
into hydrochloric acid, the hydrochlorate of tri-methylamine was 
obtained. 
In their general physiological effects these substances very closely 
resemble each other. The most obvious symptoms which they 
produce are paralysis and slight muscular spasm ; and when these 
symptoms were carefully analysed, by restricting the poisonous 
action to certain defined regions in frogs, it was ascertained that 
they are caused mainly by a direct action on the cerebro-spinal 
nervous system and on striated muscles. When large doses are 
given, the functional activity of these structures is first impaired 
and then destroyed ; but during the stage of impairment, a slight 
degree of spasmodic action is produced, which may probably be 
referred, in frogs, to the stage of irritation which precedes the final 
action of the majority of muscular poisons, and, in mammals, to this 
action, aided by changes in the vascular condition of the central 
nerve organs, due to an influence on non-striated muscles. 
The physiological effects of chloride of ammonium and of hydro- 
chlorate of tri-methylamine were found to be extremely similar, 
both in degree and in kind, and to differ, in several important 
respects, from those of iodide of tetra-methyl-ammonium. The 
two former substances are comparatively feeble in their action ; the 
latter is a poison of considerable energy. Chloride of ammonium 
