CHAP. VII.] THE CONNECTIVE TISSUES. 



287 



Dster mination of Carbonic acid. 



About 5 grammes of the bone dried at 130 C. are employed 

 for this determination, which may be conveniently effected with the 

 aid of Geissler's apparatus as figured below. (Fig 53.) 



The weighed quantity of bone is introduced through the tubu- 

 lature a into the bulb A, and then three or four cubic centimetres of 

 distilled water are added. 



The stopper a is then inserted and the stopcock b leading from B 

 is turned so as to shut off the latter from A. The stopper which fits 

 into the upper part of B having been removed, pretty strong, but yet 

 non-fuming, hydrochloric acid is poured 'into B. The stopper is then 

 replaced. The small perforated stopper e at the upper part of C is 



FIG. 53. G-EISSLER'S APPARATUS FOB THE ANALYSIS OF CARBONATES. 



now removed, and with the aid of a small funnel, concentrated 

 sulphuric acid is poured into C to about the level shewn in the 

 drawing. The perforated stopper is then replaced. The whole 

 apparatus is then carefully dried with a clean cloth, placed in the 

 balance case for half an hour and then very carefully weighed. 

 After being taken from the balance the stopcock b is momentarily 

 opened, so as to allow a small portion of the contents of B to flow 

 into A. Carbonic acid is disengaged, and this passes through 

 the narrow tube c into the wider tube d, and thence, through two 

 small holes situated near its base, it bubbles through the 'sulphuric 

 acid contained in c. The effect of this passage of the moist carbon 



