Farhow. — Depression of F reezing-poiui of Water. 



29 



Art. VI. — Depression of the Freezing-point of Water by Carbon - dioxide 



in Solution. 



By F. D. Farrow, M.Sc, Canterbury College. 



[Read before the Philosophical Institute of Canterbury, 2nd Novetnber, 1910.] 



This paper contains a brief account of the results of two series of experi- 

 ments on the freezing-point of water containing carbon-dioxide in solution. 

 The only work done in the same direction previously appears to be that 

 of Garelli and Falciola.* 



In the experiments now described the freezing was carried out in the 

 thick glass tube A of the diagram, 28 mm. external diameter, widened 



slightly at the top, and 

 sealed into the brass 

 head B by means of a 

 1 i n e n - 1 a p e collar and 

 marine glue. B was con- 

 nected by a copper tube 

 D with the brass chamber 

 E, and so with the pres- 

 sure-gauge P, the carbon - 

 dioxide bomb, the atmo- 

 sphere through H, and 

 an open mercury mano- 

 meter M through the 

 needle valve N [not 

 shown in figure]. 



The water in A was 

 stirred by a silver-wire 

 stirrer soldered to a short 

 cylinder of sheet iron 

 22 X 20 mm., which, 

 after silver-plating, was 

 covered with cycle- 

 enamel and baked. This 

 stirrer - ring enclosed 

 the thermometer, and 

 was raised and dropped 

 by an intermittent cur- 

 rent flowing in a coil of 

 No. 18 copper wire, in 

 15 layers of 41 turns each, 

 fitting loosely round the 

 top of the glass freezing- 

 I tube. The current, 2-3 



amperes, was adjusted 

 by a rheostat, and made and broken (flowing about one-third of the time) 

 by a wire dipping into a mercury-cup, and attached to a pendulum making 

 32 swings per minute. 



73 needle va.2ve, 

 h<jdrauZ: ^am.^e , 

 ojben ir^erci/rif ^auyt 



//alf secUon 

 of -freeyn^ tuhe . 



*Atti. R. Accad. Lincei, 1904 (v), 13, 1, 110-18. 

 1904, vol. 86, ii, p. 312. 



Abstract in Journ. Chem. Soc, 



