TRANSACTIONS OF SECTION B, 603 



animals carry with tbem some of the nitrogenous constitutents of the sewage which 

 they have devoured, but as yet the authors have formed no estimate of the quan- 

 tity so removed. There are also species of worms always present in the bacteria 

 beds in considerable numbers which no doubt also feed on the sewage. 



3. Humus and the Irreducible Residue in the Bacterial Treatment 

 of Seiuage. By Dr. S. Rideal. 



•i. Sulphuric Acid as a Typhoid Disinfectant. By Dr. S. Rideal. 



5. On the Inverse Relation of Chlorine to Raiifall. 

 By William Ackroyd, F.I.C. 



Rainfalls of various dates when compared among themselves appear so erratic 

 in their quantitative composition that observers have generally been satisfied with 

 monthly or half-yearly averages. When the periods of observation are shortened 

 to daily estimations, say of the chlorine, it clearly appears that minimum amounts 

 of rainfall are marked by maxima of chlorine contents, and vice versa. Thus in a 

 daily comparison where the results are plotted for tenths of an inch of rainfall and 

 parts per 100,000 of chlorine the respective curves interlock and each chlorine peak 

 has its corresponding rainfall hollow. This will be seen on following the plotted 

 observations in the diagram for Halifax, November 12, 1900, to March?, 1901. 

 It is also apparent in the diagrams for country rainfall which illustrate my paper 

 ' On the Distribution of Chlorine in Yorkshire, Part II.,' and where the observa- 

 tions are weekly. Marked parallelism of chlorine curves, where several are com- 

 pared, is regarded as being due to common causes. 



6. On the Distribution of Chlorine in Yorkshire, Fart II. 

 By William Ackroyd, F.I.C. 



All figures refer to parts of chlorine per 100,000 of water. 



As the result of many observations of minima, the chlorine is found to increase 

 from '7-1 in the west and north-west, where the rivers originate, to 1-7-2 in the 

 east and south-east, where, in the Chalk Wolds, the upturned edges of the chalk 

 drink in and store up a vast amount of rain water, which is utilised by many of 

 the East Riding communities. Beyond this there is a south-eastern area of high 

 chlorine figures formed by the triangular tract of drift ending with Spurn Head. 



Normal chlorine is affected by manufacturing centres. From observations ex- 

 tending over three months, it is shown that in a manufacturing town like Halifax 

 the atmospheric contribution through the rain is -01 part of chlorine per 288 

 people per square mile, and that the total contribution for ground as well as air is 

 •01 part of chlorine per 5-3 of the population. 



Attention is also drawn to a disturbing influence in the prevalence of high 

 winds from the sea, which send up the chlorine figures for the rainfall. 



Department II. 

 The following Papers and Report were read : — 



1. Hydration of Tin, including the Action of Light. 

 By Dr. J. H. Gladstone, F.R.S., and George Gladstone. 



The authors described a tin trade mark which had been standing in the minera- 

 lo^cal cabinet of Mr. George Gladstone for twenty-seven years, exposed on the front 



