SCIENTIFIC SUMMARY. 
105 
The Chemistry of Respiration . — Herren Pettenkofer and Volt, wko have 
added so largely to our knowledge of the physiology of respiration, have 
lately undertaken a series of researches in their large respiration apparatus 
at Munich, with a view to determining to what extent the respiratory func- 
tions vary during the day and during the night. Their first experiments 
were conducted upon a young watchmaker, aged 28 years, and led to a re- 
markable result, in respect to the difference in the amount of oxygen absorbed 
and carbonic acid evolved during the day and night periods. The experi- 
ments included one day of rest, during which the man amused himself by 
reading and repairing a small clock, and a day of labour in which he was 
made to turn a wheel heavily charged. The chief conclusions which may be 
drawn from these experiments are the following: 1st, That in 24 hours the 
volume of the CO3 eliminated is about equal to that of the O absorbed ; 
2nd, That the interchanges of gas effected by respiration go on differently by 
day and by night, so that the greater part of the 0 absorption takes place 
by night and the greater part of the COj elimination by day. Work has 
scarcely any immediate influence on the oxygen absorbed during the day, 
although it has a great immediate influence in the amount of CO3 eliminated. 
This seems to be formed at the expense of oxygen which has been stored up. 
3rd, The excretion of urea is not increased by work, although this be long 
sustained. 4th, The elimination of water is very much increased by work, 
and the increase continues during the ensuing hours of sleep. Pettenkofer 
and Voit have, we believe, since repeated these experiments on the man 
who was the subject of the above experiments, but without confirming the 
results as to the difference between the day and night periods. — Yide An- 
nalen der Chemie, CXLI. Heft 3, and Journal of Anatomy and Physiology for 
November. 
Wounds treated by a Vacuum . — MM. Guerin and Maisonneuve have almost 
simultaneously brought forward proposals similar in principle, though 
differing somewhat in detail, for the treatment of wounds by removal of the 
air. The more perfect mode is that described by M. Guerin, which is applicable 
to a large number of wounds, and which by a series of tubes may be placed 
in communication with several patients at once. The advantage claimed for 
the process is that it causes the wound to cicatrize more quickly than by the 
ordinary method. A sort of air-tight cap is placed over the wound, and 
this is placed in communication with a chamber to which is attached an air- 
pump and a tube of mercury. The amount of the vacuum is ascertained by 
the height of the mercury in the tube {inanometer'). The effects of this 
process are the prevention of the action of the air on the wound, and the 
gradual but constant removal of the unhealthy fluids formed in the healing 
tissues. 
Therapeutical Effects of Hydrocyanic Acid. — Contrary to the usual doc- 
trine, it is alleged by M. Poznanski, in a note to the French Academy, that 
cyanhydric acid is rather a stimulant than a sedative, and that as such it is 
a valuable remedy in cases of cholera. He gives it in doses of 12 drops every 
24 hours. — Vide Comptes Rendus, Oct. 7. 
The Pathology of Chlorosis . — In a paper read before the Academy of 
Sciences of Vienna, M. Duncan, of St. Petersburg!!, stated that the pallor of 
chlorotic patients does not arise from diminution of the number of the red 
