Chemistry and Physics. 349 



may be briefly expressed by saying that the acid is k times 

 stronger than the metahydroxyanthraquinone. The value of k 

 for formic acid for example is given as 61 °97 ; of acetic acid 

 14*33; of benzoic acid 20*71; paramidobenzoic acid 7*60; lactic 

 acid 39 - 94; propionic acid 11*68. The results obtained, even 

 within very wide limits of concentration, are completely in agree- 

 ment with the law of Guldberg and Waage ; but they cannot 

 be brought to accord with Ostwald's values of the affinity con- 

 stants as determined by the electrical method, even when the 

 same solvents are employed in the two cases. The authors re- 

 gard the affinity coefficients as determined by the spectrophoto- 

 meter method as expressing more simply and directly than can 

 be done by the dissociation constants, the relation which exists 

 between chemical change and the nature of the inter-acting sub- 

 stances. — Ann. Chem. Pharm., cclxx, 204, 208 ; J. C/iem. Soc, 

 lxii, 1269, November, 1892. G. f. b. 



4. On the Reaction of Hydrogen with Chlorine and Oxygen. — 

 Some time ago, in conjunction with Dixon, Harker showed that 

 contrary to the prevalent impression, hydrogen, when exploded 

 with oxygen and excess of chlorine, does not unite wholly with 

 the chlorine, but that water is formed at the same time. These 

 experiments were left incomplete and Harker has now continued 

 them with a view to determine whether the ordinary laws of 

 mass action hold in this case. Much difficulty was encountered 

 at first hi carrying out the experiments, and special apparatus 

 was devised for the purpose which is fully described in the paper. 

 In all 18 experiments were made, in which the volume of chlorine 

 added to 50 volumes of hydrogen and 50 volumes of oxygen 

 varied from 9*08 to 95*83. The results show that in all cases a 

 division of the hydrogen between the chlorine and the oxygen 

 takes place. Moreover, this division takes place in such a way 

 that the product of the number of molecules of hydrogen 

 chloride and of those of oxygen divided by the product of the 

 number of molecules of water vapor and of those of chlorine is 

 practically constant, the mean value of this constant as given by 

 the experiments being 23. The law of mass action laid down by 

 Guldbei'g and Waage holds therefore in this as in other cases. — 

 Zeitschr. physik. Chem., ix, 673; J. Hoc. Chem., lxii, 1147, Oct., 

 1892. G. F. B. 



5. On the daily variation of Gravity. — Professor Mascakt, 

 for several years has employed a barometric tube with a column 

 of mercury four meters and a half in length, which counterbalances 

 the pressure of a mass of hydrogen contained in a lateral vessel. 

 The whole apparatus is sunk in the ground with the exception of 

 a short column of mercury at the top. The level of the liquid is 

 compared with a lateral division, the image of which is formed in 

 the axis of the tube, and the points may be fixed to within the 

 -j-^-j- of a millimeter. The curves of variation present a very regu- 

 lar and slow course, due to changes of temperature, but on some 

 clays certain perturbations arise the duration of which is from 



