Dr. Smith on the Phenomena of Respiration, 439 



_ In the artificial freezing of sea-water, the ice was found to be ver- 

 tically striated, and often divisible into two or more layers, while 

 the under surface was always marked by fine lines intersecting each 

 other at definite angles. From the bottom of the vessel thin plates 

 of ice formed in the unfrozen liquid. They varied in length from 



1 in. to 2i hi., and contained less salt than the ice formed on the top. 

 To explain the observation of Dr. Kane as to the freshness of ice 



formed from sea- water under— 30°, the author supposes that it may 

 have depended on the freezing of a portion of sea-water which was 

 covered at the time of its congelation with a stratum of fresh water 

 producedby the melting of bergs. On the 12th of April, 1857, 

 whilst lying off Brown's Island, within about 4 miles of a glacier 

 surroimded by bergs, the author observed a layer of fresh water, 



2 or 3 inches in depth, floating, like oil, on the surface of the salt 

 water. To this cause he attributes the occasional occurrence of 

 hummocks from the upper portions of which ice perfectly free from 

 salt can be obtained, while on digging deeper into these hummocks, 

 the ice is always found to lose its freshness. 



"Inquiries into the Phsenomena of Respiration." By Edward 

 Smith, M.D. 



The author gives in this communication the result of numerous in- 

 quiries into the quantity of carbonic acid expired, and of air inspired, 

 with the rate of pulsation and respiration, — 1st, in the whole of the 

 twenty-foui- hours, with and without exertion and food ; 2nd, the 

 variations from day to day, and from season to season ; and 3rd, the 

 influence of some kinds of exertion. 



After a description of the apparatus employed by previous ob- 

 servers, he describes his own apparatus and method. This consists 

 of a spirometer to measure the air inspired, capable of registei'ing 

 any number of cubic inches ; and an analytical apparatus to abstract 

 the carbonic acid and vapour from the expired air. The former is a 

 small dry gas-meter, of improved manufacture, and the latter con- 

 sists of — I St, a desiccator of sulphuric acid to absorb the vapour ; 

 2nd, a gutta-percha box, with chambers and cells, containing caustic 

 potash, and offering a superficies of 700 inches, over which the 

 expired air is passed, and by which the carbonic acid is abstracted ; 

 and 3rd, a second desiccator to retain the vapour which the expired 

 air had carried off from the potash box. A small mask is worn, so as 

 to prevent any air entering the lungs without first passing through the 

 spirometer, and the increase in the weight of this with the connect- 

 ing tube and the first desiccator gives the amount of vapour exhaled, 

 whilst the addition to the weight of the potash box and the second 

 desiccator gives the weight of the carbonic acid expired. The ba- 

 lances employed weigh to the -^-^ of a grain, mth 7 lbs. in the \m\\. 

 By this apparatus the whole of the carbonic acid was abstracted 

 during the act of expiration, and the experiment could be repeated 

 every few minutes, or continued for auy number of hours, and be 

 made whilst sleeping and with certain kinds of exertion. 



The amount of carbonic acid expired in the twenty-four hours was 



