XXX Transactions of the Boyal Society of South Africa. 
portion of the waste from the acetylene machines has in some manner 
found its way to the pulsator, where the supposed mineral was discovered. 
It has been found possible to compare specimens of the substance referred 
to (kindly supplied by the general manager of the De Beers' Co.) with the 
lumps and pellets which settle in the lime residue from generators supply- 
ing acetylene gas to the Chemical Laboratory of Victoria College (Stellen- 
bosch). In chemical as well as physical characters there is an unmistakable 
similarity between the two products. Thus, (1) slaked Hme, which of 
course accompanies carbide pellets, can be detected in some of the 
cavities on surfaces of the pulsator pellets. (2) Variations in hardness, 
form, colour, fracture, size of pellets, and peculiar markings are faithfully 
reproduced. (3) In either case the lumps and pellets vary in composition 
from iron carbide, attacked by dilute acids, to iron silico-carbide, which is 
attacked by hydrofluoric acid, but not by hydrochloric and sulphuric acids. 
(4) The pellets from either source give off an odour of acetylene when 
crushed. (5) The pulsator pellets, as well as ordinary carbide pellets, do 
not contain, as far as can be found, notable quantities of titanium. In an 
iron mineral derived from the ilmenite of " blue ground," by reduction at 
a high temperature, one would certainly expect to find titanium. 
" Further Magnetic Observations in South Africa during the Years 
1910 and 1911," by J. C. Beattib. 
The communication contains the reduced results of observations in 
various parts of South Africa during 1910 and 1911 for determining the 
secular variation of the magnetic elements. It also contains results of 
additional observations in the West Transvaal and the East of Cape 
Province, with a discussion of the magnetic states of these regions. 
"Action of Eadium Salts on Glass," by W. A. Douglas Eudge. 
An account of experiments carried on during the past three years in order 
to study the prolonged action of radium salts upon glass. Small quantities 
of radium were sealed up in thick-walled tubes, and the extent to which 
the colouration extended determined by cutting up sections of the tube, 
polishing the ends, and examining with a microscope. The tint developed 
depended upon the nature of the glass employed, and the depth of 
penetration depended upon the structure of the glass. Many kinds of 
glass show a ''zonal" structure, and an abrupt change in the depth 
of colouration appears at the junction of successive zones. The, width of 
the zones were measured with a micrometer, the first and darkest being 
0-27 mm. ; the others extended right up to the external walls of the tube, 
a distance of 2*48 mm. from the bore. If the colouration is due to 
X particles alone, the range must be much greater than would be deduced 
from the experiments of Eutherford and Joly. There is evidently some 
obstacle met with to the free passage of the rays at each zonal layer, as 
the colouration shows. The action of even a very impure radium salt is 
