Proceedings of Learned Societies. 157 



and finally separating into two portions, which become independent." 

 Whatever be the means by which the separation is accomplished, in 

 the greater number of cases it was evident that, as in the exceptional 

 case recorded, the animal absolutely tore itself into halves ; and fur- 

 ther, that the division occurred in a direction from below upwards, 

 the reverse of that which is supposed by some to be the constant 

 mode in the class. 



PHILOSOPHICAL SOCIETY OP MANCHESTER.— Jan. 24 



Ox the Physiological Effects of Carbonic Acid. — Dr. Angus 

 Smith related the results obtained by some very valuable experi- 

 ments on breathing in close chambers. Dr. Smith had an air-tight 

 leaden chamber constructed, containing 170 cubic feet of air. On 

 remaining in this chamber until the carbonic acid produced by his 

 breathing, and the burning of candles amounted to 3*9 per cent, of 

 the enclosed atmosphere, he found that his pulse fell so low that he 

 was scarcely able to count the beats, which diminished rapidly in 

 number. As this effect was speedily produced, and as there was no 

 time for the accumulation in the air of any large amount of organic 

 matter, the effect must have been chiefly due to the carbonic acid. 

 The experiments were frequently repeated, each time with the same 

 results, the number of beats of the pulse diminishing as the car- 

 bonic acid increased in quantity, and the breathing quickening in 

 the same ratio. The lowest amount of carbonic acid producing 

 these unfavourable residts was found to be 0*1 per cent., an amount 

 often greatly exceeded in private houses and public meetings, where 

 it often rises to 0'2 or even 0"3 per cent. As a proof that the long- 

 continued action of an atmosphere charged with an undue quantity 

 of carbonic produces permanently injurious results, Dr. Smith 

 quoted the cases of the Cornish miners, who are remarkable for 

 the peculiarity of a feeble pulse. In Dr. Smith's experiments the 

 pulse and the breathing returned to the normal state after a few 

 minutes' exposure to fresh air, the rapid, gasping, or panting effect 

 produced by the carbonic acid quickly passing away. 



ROYAL INSTITUTIOK— Feb. 3. 



Mode of determining the Atomic Weight of an Element. 

 — Professor Odling's discourse on some new compounds of the 

 metal aluminium, although of especial interest to the chemist, 

 offered a good opportunity to every one moderately conversant with 

 science, of becoming acquainted with a most important chemical 

 doctrine. The question which has been agitating the chemical 

 world during the last few years is this : — " How can we tell the 

 true atomic weight of an element ?" In other words, " What is 

 the smallest proportion of any element, taking hydrogen as the 

 unit, which can enter into a chemical compound ?" In the annexed 

 abstract of Dr. Odling's remarks, an answer to this question, so far 



