94 Transactions of the Boyal Society of South Africa. 
pumping from No. II. began, and this at once began to effect a depression 
of the level on No. VI. 
Thus it appears that Nos. II., III., and VI. ha^ve a more or less direct 
underground connection. 
Arrangements are now being made to have an improved recording 
machine placed on No. VI. for the purpose of obtaining longer records. 
The short records already obtained suggest that the H.W. of No. VI. is 
not synchronous with that of No. V., and that there may be a time 
difference between the two amounting to several hours. Longer records, 
however, are necessary for the purpose of proving or disproving this want 
of synchronism. Various reports have reached me alleging the existence 
of fluctuations in several other sulphurous wells in the eastern part of Cape 
Colony, but I have not as yet had any opportunity of verifying them. 
Analyses of the Water and Gas of the Tarha Bridge Wells. 
A sample of the water which I took from No. V. in 1905 was analysed 
by Mr. John D. Eose, of the Government Analytical Laboratory. The 
following are Mr. Eose's analytical results : — 
In Grains 
per Gallon. 
Total solids at 180^ C 38-80 
Silica 1-78 
Oxide of iron and alumina 0-06 
Lime 3-82 
Magnesia 1*23 
Alkalies calculated as Na 13-67 
Chlorine 13 79 
Sulphuric oxide 0-33 
Combined carbonic dioxide 5-33 
" All the lime and magnesia are present as carbonates, with a trace of 
calcium sulphate, while sodium chloride appears to be the chief mineral 
constituent. The spectroscope reveals the presence of a very minute 
quantity of lithium. Potassium is also present in small quantities as 
shown by the flame reaction." 
Mr. Eose did not attempt to estimate the dissolved gases, but part at 
least of the sulphuric oxide figuring in his analysis is probably due to 
oxidation of the sulphuretted hydrogen contained in the water as it issues 
from the well. The odour leaves the water after it has stood exposed to 
the air for a few hours. I have found that the water of all the Tarka 
Bridge wells tested on the spot immediately after collection, yields with 
cadmium chloride solution a considerable precipitate of yellow cadmium 
sulphide. 
