46(5 
DR. J. 11. VINCENT ON THE DENSITV AND COEFFICIENT 
cool, while the vessel into ’which c dipped was kept boiling ; the side of the tnhe 
a h then became completely tilled with air-free water, and the point a was then 
sealed off. By weighing before and after tilling with water, the mass of water taken 
was olffained. The other lindj of the U-tube ’was now filled with mercury, and the 
water was frozen by subjecting it to cold in such a way that the water froze ffom 
above downwards. The ice thus formed was absolutely clear. The cork and capillary 
tulje slnwvii in the figure ’were then inserted, and the whole apparatus surrounded 
with dry snow. The mass of the vessel B and its contained mercury was noted. On 
melting and again reducing to 0°, re-weighing the vessel B provides the other datum 
requisite to conq)ute the density of ice at 0° C. Bunsen’s mean value was ‘DlGfT. 
No experiments on these subjects seem to have been published again until quite 
i-ecent times, when Nichols brought out his paper on the density of ice in 1899 
(‘Physic. Beview,’ vol. 8, January, 1899). Leaving the theoretical jiortion of this 
memoir out of consideration for tlie present, we find that Nichols determined the 
density of artificial and natural ice by several methods. 
Method 1. Specific Gravitij Bottle. —The apparatus consisted of a specific gravity 
bottle fitted with a tube (see fig. 3), round ’which a cylinder of ice was formed. The 
unfrozen water was shaken out, and the whole again subjected to cold: 
by Aveig’hing in a laboratory, whose teniperature was below freezing point, 
the mass of ice taken ’was found. The bottle was now filled up with cold 
mercury, the stopper inserted, and the whole left in an ice bath oveiiiight 
with the stopper dipping in mercury. Finally, the stopper was dipped 
iido a w^eighed quantity of mercury, the ice permitted to melt, and the 
Avhole apparatus again reduced to U° Ft The loss of weight of the 
mercury into which the stopper dipped, gave the means of computing 
the density of the ice mantle at 0° C. free from any error due to defoiina- 
tion of the Task on filling with mercury. The result for the density from a single 
experiment was ’91619. 
Method 2. Brunner’s Metliod. — Nichols employed refined petroleum, and 
weighed seyeral varieties in it, again working in a laboratory below freezing point. 
The results were reduced to 0° C., by employing the value '00015 for the coeflicient 
of culiical expansion. The results obtained were - 
Kind of ice. 
Densit}^ at 0“ C. 
Kind of ice. 
Densit}' at h” C. 
Artificial. 
■91603 
Natui'al. 
■91792 
Natural. 
•91795 
(new pond ice) 
Natural. 
■91632 
(icicles) 
(pond ice, 1 year old) 
Method 3. Determination ofi the Volume oj the Ice hy Displacement. — Nichols 
next attacked the question by the enqiloyment of an absolutely original method. An 
