346 DR. STEVENS ON THE THEORY OF RESPIRATION. 



pump was used, globules were observed to escape from the blood, which passed 

 through the barytic water, but the transparency of the latter was not affected. 



The annexed sketch is a representation of an apparatus which was invented by 

 Mr. Squire, of Duke Street, Grosvenor Square, and used in the fol- 

 lowing experiments. To a double-necked pint bottle, a, two glass 

 tubes were fitted, one, b, ascending, the other, c, descending. The 

 ascending tube is terminated by an air-tight box, having an aper- 

 ture, over which a slide is moved by means of a strong wire. The 

 descending tube is terminated by a brass orifice, which is closed at 

 pleasure by a brass cap, having a cone in the centre surrounded with 

 leather, and moved with a sliding wire, d represents a four-ounce 

 phial with a loop of wire round the neck, by which it is connected 

 with the descending tube. The phial was filled to the double line 

 with distilled water. 



3. The pint bottle and both tubes being filled with pure hydrogen gas, the ori- 

 fice of the upper tube was placed on the skin, near the bend of the arm ; a vein was 

 then opened, and the orifice slid carefully along until it included the incision which 

 had been made by the lancet. The valve was opened, and as the blood passed into 

 the bottle, hydrogen was expelled through the descending tube, the orifice of which 

 was immersed in distilled water. As soon as five or six ounces of blood had entered 

 the bottle, both the orifices were carefully closed. The orifice of the descending tube 

 was then immersed in barytic water, and the valve being opened, the whole was 

 placed under the receiver of an air-pump. In proportion as the air was removed, 

 the hydrogen, as well as any gas that might escape from the blood, passed through 

 the barytic water, without, however, producing the slightest change in its trans- 

 parency. 



From the first of these experiments it might be inferred that a gas is capable of 

 being removed from venous blood by the air-pump : but this supposition may pos- 

 sibly be erroneous ; for similar globules appear to arise when we use water, even 

 after it has been boiled and then cooled in a close vessel to 98°. The second expe- 

 riment shows that this appearance is not due to the escape of carbonic acid ; and 

 from the third experiment it is very obvious that carbonic acid cannot be so obtained 

 from venous blood which has not been exposed to air. 



4. About four ounces of serum were put into a Hope's eudiometer, the upper divi- 

 sion of which contained four tenths of a cubic inch of carbonic acid : they were 

 agitated together, and after a few minutes the serum had absorbed the whole of the 

 acid. This impregnated serum, without being exposed to the air, was transferred into 

 the double-necked pint bottle, which had previously been filled with hydrogen, and 

 which was immediately put under the receiver of the air-pump. When the pump 

 was used, the hydrogen, as well as the gas which appeared to escape from the serum, 

 passed through the baiytic water ; but its transparency was not affected. 



