MancJiester Memoirs, Vol. Hi. (1908), No. 14. 7 



fitted up with bottles containing a sufficient quantity of 

 the necessary reagents. The iodide and sulphuric acid 

 were measured from a small graduated cylinder, and for 

 the titrations a narrow graduated pipette, such as is used 

 for bacteriological work, was employed. The whole kit 

 thus occupied very little space. The thiosulphate solution 

 being kept in the dark was found to alter only very 

 slowly. It was retitrated against centinormal iodine on 

 May 28th, after returning to Manchester. By that time 

 a distinct deposit of sulphur had taken place, which was 

 not noticed previously. Even then the correction required 

 was not excessive. The results of the observations in 

 the Mediterranean were adjusted accordingly, and the 

 amended figures are given in brackets in the table. They 

 are, however, certainly to be taken as minimum figures. 

 A study of the table will show, in the first place, as might 

 have been expected, that the chemical intensity is greatest 

 in the middle of the day. It is also evident that the 

 chemical activity is greater out at sea than inland, and 

 that even in the Mediterranean higher results are obtained 

 than in Calcutta or Agra. 



Through the kindness of Dr. Bailey the writer is 

 enabled, in Tabids IV. and V., to include for comparison 

 a number of hitherto unpublished records, chiefly obtained 

 in Manchester, but also including observations made in 

 other parts of England and the Continent. 



The results set out in Table IV. are calculated in the 

 same terms as those already given, and for the most part 

 are taken under conditions of full sunlight, and are, there- 

 fore, comparable throughout. In the case of the results 

 in Table V., with the exception of those at Pontresina, 

 it is not quite certain whether there was full sun all the 

 time. 



