ON SEISMOLOGICAL INVESTIGATIONS. 



79 



metric registration, it was necessary to examine the theory of the latter, 

 when the direction on the paper is defined by means of sudden motions 

 from a state of rest. By analysis similar to that given above it may be 

 shown that the numbers for the lag of the galvanometer behind the 

 pendulum, given byGalitzin in his Table VII., are also based on a definition 

 differing by half-a-period from that here taken. So that the sum of the 

 lags given in Galitzin's Tables VI. and VII. — ^that is to say, the lag of the 

 galvanometer behind the ground — ^is in agreement with the definition here 

 taken. Of course, it is arbitrary as to a whole number of wave-lengths. 



In fig. 3 the crosses indicate the lag found for the Milne-Shaw in- 

 strument, taking the lag calculated for the Galitzin instrument as correct. 



The Study of Hydroaromatic Substances. — Report of the Com- 

 mittee, consisting of Professor W. H. Perkin {Chairman) , 

 Professor A. W. Crosslby (Secretary), Dr. M. 0. Forster, 

 Dr. H. E. Le Sueur, and Dr. A. McKenzie. 



1. Bromoxylenols obtained from dimethyldihydroresorcin.^ The 

 transformation of certain hydroaromatic substances into bromoxylenols, 

 alluded to in the last Eeport,- has now been completed. 



2. Derivatives of Isopropyldihydroresorcin.' The preparation and 

 properties of l-isopropylcyclohexan-3-ol and l-isopropylcyclohexan-3- 

 one, briefly referred to in the last Eeport, have been described in detail. 



3. Dihydric Alcohols obtained by the reduction of substituted 

 dihydroresorcins.^ It Has been shown that 1 :3-dibromo-derivatives of 

 the saturated cyclohexane hydrocarbons may be used for the preparation 

 of substituted cyclohexadienes.^ It would appear that a more expedi- 

 tious method of preparing these substances would be from the dihydric 

 alcohols, which, on theoretical grounds, should be easily obtained by the 

 direct reduction of the dihydroresorcins, 



CMe^ 

 H,C(^\cH, 

 HO . C^vJcO 



H,C 

 HO. HC 



CMe 



CH. 



CH, 

 CH . OH 



but though many attempts have at vax'ious times been made to bring 

 about these reactions, in some cases resulting in the isolation of small 

 quantities of the desired substances, it is only comparatively recently 

 that conditions have been worked out for the pi'eparation of the dihydric 

 alcohols in quantity. 



Knoevenagel ® obtained small amounts of phenylcyclohexane-3 : 5- 



1 J.C.S., 1914, 105, 165. 

 » J.O.S., 1915, 107, 171. 

 « J.C.S., 19D8, 92, 629. 



2 Eeports, 1913, p. 135. 

 * J.C.S., 1915, 107, 602. 

 6 AnnaUn, 189;j, 289, 167. 



