ON THE SOLIDIFICATION OF CARBONIC ACID. 313 
coldness is increased. At 32° the cylinder is about half an 
inch in length. 
Carbonic acid, mechanically powerful as it is, is not appli- 
cable, perhaps, either to locomotion or projection; but though 
the reasons for this are most of them obvious, the Franklin 
Institute has appointed a committee to investigate and report 
on the subject, that the exact truth may be known, and the 
waste of time and talent, likely otherwise to be experienced, 
be saved to the country. 
Journ. Franklin Institute, 
Professor J. W. Bailey, of West Point, has repeated, with the 
above described apparatus, some of the experiments men- 
tioned, and " with complete success." We avail ourselves 
with pleasure of Mr. B.'s permission to publish that part of 
his letter to Dr. M., dated Dec. 13th, 1838, containing a con- 
firmation of these results, and this the more especially on 
account of the novel and interesting observation concerning 
the crystallization of mercury while freezing. 
" I have now the pleasure to inform you, that I repeated 
your beautiful experiments on the solidification of the gas, the 
freezing of mercury, &c, with complete success. I procured 
from one charge of materials enough of the solid CO 2 to more 
that half fill the tin receiver; and by means of this I froze 
into one mass about 1400 grains of mercury, and might easily 
have frozen a much larger mass. I observed, as the mercury 
began to freeze, the shooting of lines of crystallization over 
its surface." " After freezing the mercury I sent to the 
quarters of several friends to invite them to come and see it, 
and I was able to retain it frozen until they arrived ; they 
were much delighted with the sight of the novelty. I showed 
them its sectile character, and its shortness just before melting, 
its sinking in liquid mercury, &c. The experiments on the 
liquefaction of carbonic acid are so easily made with your 
apparatus, that it is scarcely necessary to state that I have 
performed them successfully." 
