562 MR G. CARR ROBINSON ON 
substances, the tar was subjected to the following treatment, viz. :—It was 
neutralised with caustic soda, and the crude bases so separated distilled; the 
distillate was then dissolved in dilute sulphuric acid, allowed to stand some 
time to separate tarry matter, and the aqueous solution once more neutralised 
with caustic soda, when the bases so liberated were distilled off from an excess 
of caustic soda and potash. The semi-purified bases were now dissolved in the 
naphtha known as ‘ colourless vil,’ s.g. 760, in the proportion of four parts 
naphtha to one part bases, and after standing some hours, the bases were 
dissolved out with dilute sulphuric acid, and the acid solution once more 
neutralised with caustic soda. The separated bases were then digested in an 
iron still connected with an inverted condenser, with an excess of caustic soda, 
for twelve hours, and then distilled off from the alkali; this last process of 
digestion was repeated a second time, when the bases were considered 
pure.” 
In addition to the above purification process, the bases had undergone 
twelve complete fractional distillations, in order to obtain specimens of leuco- 
line, iridoline, and cryptidine ; and only that portion of the distillate boiling 
above 315° C. was forwarded to me, and to which my examination was con- 
fined. 
The mixed bases, about 1 kilogram, said to boil above 315° C., were frac- 
tionated three times, the distillate being received in two portions, —that boiling 
between 305° and 320° C., marked A; and that boiling above 320° C., 
marked B. 
The high boiling bases, B, were dissolved in dilute hydrochloric acid, the 
solution filtered, then saturated with caustic soda, the separated bases washed 
with water, dried with sticks of caustic potash, and distilled off. 
Attempts were then made to get crystallisable salts from the mixed bases ; 
the double chlorides of platinum, gold, cadmium, mercury, lead, and zinc were 
tried, but without success, only resinous sticky masses being obtained ; the 
same failure in getting crystallisable salts was experienced when the bases were 
treated with sulphuric, hydrochloric, nitric, and oxalic acids. It was thought 
that separation of the bases might be effected by converting them into methyl- 
or ethyl- iodide compounds, as GREVILLE WILLIAMS, “ Trans. R.S.E.,” vol. xxi, 
obtained well-defined crystalline salts in this way. This method was tried, 
reference to which will be made in another part of this paper, but it was not 
entirely satisfactory ; for though the methyl-iodide compounds are crystal- 
line, they decompose somewhat readily, and this method of separation was 
abandoned ; and fractional distillation, though such a tedious and wasteful pro- 
cess, was resorted to. 

