THE CHEMICAL EXAMINATION OF THE MATERIALS FROM FUNAFUTI. 363 



calcium as oxalate, and the magnesium as pyrophosphate. In the earlier analyses, 

 the calcium oxalate was converted by ignition into oxide, and weighed in that state, 

 but in the later part of the work it was found more convenient to convert it into 

 sulphate before weighing. 



On the arrival in the following year of the remaining 416 feet of core, this work 

 of chemical examination was continued by the analysis of twenty more samples, 

 taken at intervals, ten of these being executed by Dr. C. G. Cullts and ten by 

 Dr. E. W. Skeats. In making these analyses, my assistants were greatly aided 

 by the advice given to them by Dr. W. A. Tilden and the members of the Chemical 

 Staff of the Royal College of Science. 



As the interesting and sometimes rapid changes in the proportions of calcium and 

 magnesium in the cores came to be recognised by means of these analyses, the 

 desirability of a more expeditious method of determining the relative amounts in which 

 the two bases were present became apparent. After consultation with Dr. Tilden 

 and the members of the Chemical Board of the Government Grant Committee 

 of the Royal Society, it was determined to adopt the volumetric method for the 

 estimation of the calcium, by titration with potassium permanganate. The amount 

 of phosphates and other materials in all parts of the core had already been shown to 

 be exceedingly minute, and consequently the magnesium could be safely estimated 

 by difference. Funds for the purpose having been supplied by the Government 

 Grant Committee of the Royal Society, the work was entrusted to Mr. J. Hart- 

 Smith, and was carried on in the laboratories of the Chemical Division of the Royal 

 College of Science under the supervision of Dr. Tilden. The accuracy of these 

 volumetric analyses was tested from time to time by the ordinary gravimetric 

 methods. 



Sixty-three volumetric analyses of the materials from the Main Boring, with 

 nineteen analyses of samples from the two earlier borings of Professor Sollas (some 

 of these analyses being in duplicate), were made l:)y Mr. J, Hart-Smith. 



At a later date, Dr. E. W. Skeats made in the Geological Research Laboratory 

 twenty more volumetric analyses, by the same method, of samples taken from the 

 Main Boring, and of fifty-three of samples taken from Professor Sollas' borings. It 

 will thus be seen that the conclusions in the following pages are based on 133 

 analyses of samples from the Main Boring — fifty of these analyses being gravimetric 

 and eighty-three volumetric — and seventy-two analyses of samples from Professor 

 Sollas' two borings, nearly all of which were volumetric. 



2. General Results op Analyses of the Cores. 



The general results arrived at by these analyses, so far as they relate to the Main 

 Boring, are represented graphically in fig. 23, a, b, c, d, from which it will be seen that 

 samples were taken generally at intervals of 10 feet, but where rapid changes were 



3 A 2 



