A NEW CAPE THERMAL CHALYBEATE SPRING. 203 



In common with most deep-seated springs, that at Zwart- 

 kops contains g-ases in solution. These were collected by Mr. J. 

 Muller, Government Analyst at Grahamstown, and sent by the 

 Company to Sir James Dewar for analysis. He found the gas to 

 consist of : — 



Carbon Dioxide 3-43% 



Oxygen ii.54% 



Nitrogen, Hydrogen, Helium, and Neon... 85.03% 



In 1,000,000 parts of gas from Zwartkops the Hydrogen, 

 Helium and Neon are 741 parts, while at King's Well, Bath, 

 England, they form 1,516 parts of the gas in solution. 



The Iron content of the spring has been subject to considerable 

 variation, the author having found quantities varying from 0.8 to 

 i.o grain per gallon of Ferrous Carbonate, while Sir Wm. 

 Crookes obtained as much as 3.78 of Ferrous Carbonate from 

 a sample drawn in December, 1909. The amount seems now to 

 remain constant at about 1.7 grains per gallon. At times the 

 odour of sulphuretted Hydrogen has been noticed, but it is doubt- 

 ful whether this gas is present in the Thermal chalybeate water. 

 Other springs had been tapped in the course of the work, some 

 of which reach the surface outside the casing, and it seems most 

 probable that the gas in question comes from one of these. 



Bath rooms have been erected at the spring, and many patients 

 have taken the waters, apparently with very beneficial results. 

 As a table water it is very palatable when charged with carbonic 

 dioxide, this gas also completely preventing the precipitation of 

 the Iron which otherwise takes place on exposure to air. The 

 Eastern Province is to be congratulated on the possession 

 of so valuable a spring, and it is to be hoped that the owners will 

 soon afford facilities for those who cannot afford the long journey 

 to, and luxury of, the famous Caledon Spring to utilize the very 

 similar water which has now been discovered in their midst. 



COMETARY ORBITS.— Mr. R. T. A. Innes contributes 

 to the December issue of the Monthly Notices of the Royal Astro- 

 nomical Society a paper on the mean or perihelion distances of 

 comets. The author summarises his discussion of the subject 

 thus : — 



" The elliptic equation between the mean motion and the semi-axis major 

 does not hold in the solar system. In the cases of minor planets and with 

 comets with large distances, the error in the mean distance (or perihelion dis- 

 tance of parabolic orbit) deduced from the elliptic formula will affect the 5th 

 significant figure. Unless the Gaussian constant is suitably modified, it will be 

 impossible to get a complete reconciliation between observation and theory." 



Mr. Innes ascribes the inconclusive results of so many inves- 

 tigations of comets' orbits to the neglect to apply to tlie equa- 

 tion of planetary elliptic motion the correction rendered necessary 

 when there are more than two bodies concerned, and hence in the 

 case of comets. This neglect makes the velocity depend on one 

 conic section and the radius vector on another. The consequence 

 is erroneous geocentric co-ordinates, and accordingly an imprac- 

 ticable ephemeris. 



