12 Transacfioiis. 



In order to ascertain what work had been done in connection with the 

 acid properties of CO2 solutions, a thorough search was made in all the 

 available journals — viz., the "Journal of London Chemical Society," the 

 " Philosophical Magazine," the " American Journal of Physical Chemistry," 

 and " Zeitschrift fiir Physikalische Chemie." Nearly all the references were 

 found in the first of these. It is very improbable that any valuable work 

 done would escape notice in its abstracts ; and, indeed. Walker and 

 Cormack, reviewing in a preface to one of their theses the work known to 

 them as having been done, mention none which is not referred to in this 

 journal. 



In searching the journals special attention was paid to the records of 

 conductivity experiments, it being felt that the electrical conductivity 

 method was much the best of approaching the subject of degree of ioniza- 

 tion, if not the only practicable one. At the same time attention was 

 paid to every detail concerning CO, solutions which could possibly bear 

 on the subject, especially to solubility at different pressures and tempera- 

 tures, and the formation of hydrates. 



Bibliography. 



The Combination of Carbon-dioxide and Water, U'roblewski, 1882 (Journ. 

 Chem. Soc, vol. 42, p. 692). — The author (who first discovered the existence 

 of a hydrate of CO,) infers that a definite but readily dissociable hydrate 

 exists " capable of existing only under certain pressures, increasing with 

 the temperature, and equal to 12-3 atmospheres at 0° C." 



The Composition of Hydrated Carbonic Acid, Wroblewski. 1882 (Journ. 

 Chem. Soc, 42, 1026). — The author concludes that at a temperature of 0°, 

 and imder the pressure of about 16 atmospheres, CO, unites with water to 

 form a hydrate CO28H2O. 



Law of Solubility of Carbon-dioxide in Water at High Pressures, Wrob- 

 lewski, 1882 (Journ. Chem. Soc, 42, 1021). — From this abstract it seems 

 {inter alia) that the author had been able to form the hydrate only in small 

 quantity, at the free surface of the solution, and the exj^eriment seems to 

 have been complicated by the freezing of the water. 



The Electric Conductivity of Solutions of Carbon-dioxide, Pfeif^'er, 1885 

 (Journ. Chem. Soc, 48, 212 ; original paper in Ann. Phys. Chem. (2), 23. 

 625-50, to which there was no access). — Pfeiffer was the first to definitely 

 investigate the conductivity of CO, solutions under varying pressures. 

 He worked with pressures of from 1 to 25 atmospheres, and apparently at 

 ordinary temperatures. His results, in effect, were — (1.) Conductivity is 

 in every case very small ; under normal conditions it equals ^\f of that of 

 spring water. (2.) If all the dissolved CO, were converted into ionized 

 H2CO3 its conductivity should be more than 1,000 times as great as observed 

 value. (3.) Change of pressure produces no alteration in the conduc- 

 tivity. (4.) Conductivity increases rapidly with increase of temperature : 

 cf. with acetic and oxalic acids (this statement is not made at all clear 

 in the abstract : temperature seems to be confused with dilution). 



Conductivity of Aqueous Solutions of Carbon-dioxide, Knox. 1895 (Jouni. 

 Chem. Soc, 68, ii, 100). — Conductivity was determined by KohlrausclTs 

 method, experiments being made at varying pressures, results being re- 

 corded for both rising and falling pressures, and at temperatures of 12-5' 

 and 18°. All of his work appears to have been done with comparatively 

 weak solutions, the most concentrated solution mentioned in the table of 



