460 
ME. C. GEEVILLE WILLIAMS OX SOME OF THE PEODHCTS 
of which is, that, contrary to what has been found to hold with organic bases, isomeric 
radicals have the same, or nearly the same boiling-points, thus : — 
Ethylbutyle=C‘=^H*^ 
Boiling-point. 
62° 
Ethylamyle=C'^ H’®. 
BoiUng-point. 
88 ° 
Amyle=e'’H^^ 
BoUing-point. 
158° 
Propyle=C^^ 
Boiling-point. 
65° 
Methylcaproyle=C'^ H'®. 
Boiling-pomt. 
82° 
But}dcaproyle=C^ H^-. 
Boiling-pomt. 
155°. 
If we consider the great difficulty of obtaining the radicals absolutely pure, we cannot 
be surprised at the fact that these numbers do not exactly accord. 
It is not unworthy of note, that the great difference in the boiling-points of propyle and 
butyle from Boghead naphtha, which might have been ui’ged as evidence against the view 
I have taken of their constitution, is, in fact, strong proof of the coiTectness of it, for 
the amount of that difference is 53° or 26° for H^, which happens to be the number 
occurring most frequently with the simple and compound radicals, and, moreover, it 
causes the Boghead propyle to have almost exactly the boiling-point of its isomer, 
ethylbutyle. 
With regard to the fact of isomeric bases differing in boiling- 
point while isomeric radicals appear not to do so, it remains to be 
seen how much in the former case the variations are caused by 
difference of type. 
In making the vapour-density determinations, I have endea- 
voured to find a method of shortening the time required for the 
performance of some of the operations. One of the points to which 
I turned my attention was, to avoid the necessity of filling the 
balloon a second time with mercury or water in order to deter- 
mine the residual air. For this purpose, as soon as the point of 
the balloon has been broken off under mercury and the latter has 
entered the globe, it is to be placed on a straw ring beneath a 
burette filled with the metal, as in the engraving. The tube is 
divided into cubic centimetres and fractions. Having so adjusted 
the position of the balloon that the fine tube from the burette just 
enters the neck, the screw a is turned sufficiently to allow a slow 
stream of metal to flow until the condensed fluid exactly airives 
at the opening, the altered level in the burette is then read off. 
It is evident that the difference between the fii’st and second read- 
ings indicates a quantity of mercury exactly equal in volume to the 
residual air. The condensed fluid being removed with the pipette, the tap is again 
