272 ANNUAL OF SCIENTIFIC DISCOVERY. 



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lines. Since these successful experiments were made, thallium, so 

 called from its green line, was discovered in 1861 by Mr. Crookes ; 

 and a fourth metal, named indium, from its indigo-colored baud, was 

 detected by Prof. Richter, of Frieberg, in Saxony, in a zinc ore of the 

 Hartz. It is impossible not to suspect that the wonderful efficacy 

 of some mineral springs, both cold and thermal, in curing diseases, 

 which no artificially prepared waters have as yet been able to rival, 

 may be connected with the presence of one or more of these elemen- 

 tary bodies previously unknown ; and some of the newly-found ingre- 

 dients, when procured in larger quantities, may furnish medical 

 science with means of combating diseases which have hitherto baflled 

 all human skill. 



While I was pursuing my inquiries respecting the Bath waters, I 

 learned casually that a hot spring had been discovered at a great 

 depth, in a copper-mine near Redruth, in Cornwall, having about as 

 high a temperature as that of the Bath waters. It seems that, in the 

 year 1839, a level was driven from an old shaft so as to intersect a 

 rich copper-mine at the depth of 1,350 feet from the surface. Through 

 this metalliferous fissure, a powerful spring of hot water was observed 

 to rise, which has continued to flow with undiminished strength ever 

 since. At my request this water has been analysed by Prof. Miller, 

 who finds that the quantity of solid matter is so great as to exceed by 

 more than four times the proportion of that yielded by the Bath waters. 

 Its composition is also in man}* respects very different ; for it contains 

 but little sulphate of lime, and is almost free from the salts of magne- 

 sium. It is rich in the chlorides of calcium and sodium, and it contains 

 one of the new metals, caesium, never before detected in any mineral 

 spring in England ; but its peculiar characteristic is the extraordinary 

 abundance of lithium, of which a mere trace had been found by Prof. 

 Roscoe in the Bath waters ; whereas in this Cornish hot spring this 

 metal constitutes no less than a -^ part of the whole of the solid con- 

 tents, which, as before stated, are so voluminous. 



Lithium was first made known in 1817 by Arfvedsen, who extracted 

 it from petalite ; and it was believed to be extremely rare, until Bun- 

 sen and Kirchhoff, in 1860, by means of spectrum analysis, showed' 

 that it was a most widely diffused substance, existing in minute 

 quantities in almost all mineral waters in the sea, as well as in milk, 

 human blood, and the ashes of some plants. It has already been 

 used in medicine, and we may therefore hope that, now that it is 

 obtainable in large quantities, and at a much cheaper rate than before 

 the Wheel-Clifford hot spring was analyzed, it may become of high 

 value. 



Mr. Warington Smyth, who had already visited the Wheel-Clifford 

 lode in 1855, re-examined it in July last, chiefly with the view of re- 

 plying to several queries which I had put to him ; and in spite of the 

 stifling heat, ascertained the geological structure of the lode and the 

 exact temperature of the water. This last he found to be 122 Fahr. 

 at the depth of 1,350 feet ; but he scarcely doubts that the thermometer 

 would stand two or three degrees higher at a distance of 200 feet to 

 the eastward, where the water is known to gush up more freely, ' The 

 Wheel-Clifford lode is a fissure varying in width from 6 to 12 feet, 

 one wall consisting of elvan or porphyritic granite, and the other of killas 



