612 
DR. A. GAMGEE ON THE ACTION OF NITRITES ON BLOOD. 
From 100 volumes of arterial blood of the Dog he obtained from about 49*5 to 54 
volumes of total gases at 0° C. and 760 millims. pressure, containing from 12 ’43 to 18*42 
volumes of oxygen, and from 26*25 to 34*75 volumes of carbonic acid, besides from 2*83 
to 5*04 volumes of nitrogen. By his method Meyer was, however, only able to get a 
small proportion of the carbonic acid in a free condition, by far the larger proportion 
only being evolved on the addition of an acid ; tartaric acid was, therefore, in his expe- 
riments, always added to the blood after the free carbonic acid had been boiled off, and 
then the more firmly combined carbonic acid was obtained. 
The very small amount of carbonic acid which could be obtained by Meyer’s method, 
without the addition of acid, was probably due to the blood having been mixed with 
from ten to twenty times its volume of water before being boiled out; for all more 
recent experimenters who have used the mercurial pumps for exhausting blood, and 
who have boiled the undiluted blood in vacuo , have succeeded in boiling off the greatest 
portion of the carbonic acid of the blood without adding any acid. 
Ludwig, and his pupils Setschenow and Schoffer, were the first to use the modern 
mercurial pump (which, as modified by Geissler, has proved so invaluable in researches 
on the blood) for the purpose of extracting the gases of the blood. 
Professor Pfluger, with the aid of Geissler, of Bonn, has succeeded of late years in 
constructing the most perfect mercurial pumps. This physiologist has not only insisted 
upon the necessity of exposing the blood to a true Torricellian vacuum, as Ludwig and 
his pupils had done, but contended that an arrangement whereby the gases of the 
blood were freed from all watery vapour was essential in order to obtain, without the 
addition of acids, all the carbonic acid of blood. His determinations made with the dry 
vacuum (das trockne vacuum) are probably the most correct which we yet possess 1 . 
Becently Pfluger has recommended that, in addition to having a drying chamber (con- 
taining sulphuric acid) in connexion with the blood-receptacle, as large a vacuum as 
possible should be employed, i. e. the vessel containing the blood to be exhausted should 
be connected with vessels of very large capacity, in which a Torricellian vacuum has been 
obtained; by this method he finds that the gases may be obtained from blood in as many 
minutes as the process formerly occupied hours, and that the amount of oxygen obtained 
is indeed greater when a large than when a small vacuum is employed. 
The following Table exhibits the mean of the most recently published experi- 
ments of Pfluger on the gases of arterial blood. 
At 0° C. and 0 m- 76 pressure. 
At 0° C. and 1 metre pressure. 
Total gases 
58-3 vols. 
44'9 vols. 
Oxygen 
22*2 „ 
16*9 „ 
Carbonic acid 
34-3 „ 
26-6 „ 
Nitrogen 
1*8 „ 
1*4 „ 
1 Pfi/ctgek, “ Die Normalen Gasmengen des arteriellen Blutes nacb verbesserten Methoden.” Centralblatt fiir 
die Med. Wissenschaften, 26 October 1868. 
