OCTOBEB 1, 1894.] 



KNOWLEDGE. 



229 



ON THE ORIGIN OF THE GOLD OF QUARTZ VEINS. 

 To the Editor of Knowledge. 



Dear Sir, — Although the article by Mr. Henry Louis "On 

 the Origin of the Gold in Quartz Veins," following one 

 of mine on the same subject, does not call for a reply from 

 me, since it is a very fair statement of another view of a 

 matter on which widely different opinions are inevitable 

 and legitimate, yet some of the observations in this 

 interesting article suggest my adding a few words to what 

 I have already written, in further elucidation of one or 

 two points that were perhaps treated too brietiy. 



The hypothesis I endeavoured to state is not by any 

 means essentially a " descensionist " one, since it allows of 

 lateral transmission of solutions into incompletely filled 

 up fissures, as well as entrance from above, for it derives 

 the mineral matter of vein-stuff from the adjacent massive 

 rocks — the rocks, in fact, traversed by the veins. 



The volcanic evidence adduced against a plutonic origin 

 for the gold of quartz vems may certainly be called 

 negative, but irom the nature of the case it has an im- 

 portant positive value, which is not lessened by one or two 

 exceptional instances to the contrary. It is not disputed 

 that some gold may exist at plutonic sources, and may 

 therefore occasionally be thence brought to the surface by 

 volcanic action, but it is the source of the great bulk of 

 the gold which exists in quartz veins that is the question 

 to be determined. A proportionally large space was 

 occupied by this volcanic evidence because, so far as I 

 know, it is evidence that has not been brought into the 

 controversy by any other writer on the subject, therefore 

 it seemed to deserve conspicuous notice. 



The instances of Steamboat Springs and Sulphur Bank 

 do not appear to me to have any contrary weight, for they 

 do not afford examples of mineral matter brought ujj from 

 deep-seated sources by volcanic action, but merely of such 

 matter brought from the adjacent rocks by hydro-thermal 

 action, exactly in accordance with one of my postulates. 

 And with respect to the Mount Morgan gold-bearing quartz, 

 even if it be the production of an old geyser, it is but 

 siliceous sinter similar to that deposited around the geysers 

 of the present day, and that is all derived by hot water 

 from rocks near the surface which, though heated by 

 volcanic action, may not be volcanic rocks A geyser, 

 therefore, although its intermittent energy is doubtless due 

 to volcanic action, is not volcanic in the sense of bringing 

 to the surface mineral matter from the deep interior. 



There is another point which seems to require explana- 

 tion. The precipitation of metallic gold from a soluble 

 salt is from soluble salts of gold in the sea that I suggested 

 would be the result of the action of dead organic matter 

 at the sea bottom, and would consequently only affect the 

 amount of auric solution in the lowest water-stratum, and 

 so, although the precipitation would be continuous in 

 consequence of convection, it would only very slightly 

 lessen the aggregate amount of gold in the entire oceanic 

 volume of water. Thus the existence of a generally diffused 

 solution of gold in the sea is not inconsistent with the 

 precipitation supposed. 



I am glad to find Mr. Louis so much in agreement with 

 me, especially as to gold being taken into quartz veins by 

 the same agency as the silica, and that the sedimentary 

 rocks themselves contain gold. This last fact is to my 

 mind a most pregnant one, since the materials of these 

 rocks are deposited matter. I know of no other source 

 for that deposited matter than the contents of the sea, and 

 hence I am inclined to credit the sea-water with giving to 

 its more bulky sediments the extremely small amount of 

 gold they contain, even when their auriferous vein-quartz 

 is included. 



Respecting the final stage in the series of operations 

 constituting the hypothesis I ventured to formulate, I may 

 perhaps say that the separation of minerals by the segre- 

 gation of their molecules from other associated mineral 

 matter is such a common geological phenomenon that its 

 employment to account for the separation of gold, and its 

 consequent presence in the metallic state in quartz veins, 

 does not seem to me to be unwarrantable. 



As Mr. Louis justly says, the subject is a difficult one, 

 but it has certainly greatly advanced in my own recollection. 

 In the days of Murchison and Forbes the igneous Origin 

 of gold held the field, and the latter of these two high 

 authorities (I know from personal intercourse with him) 

 held that now almost obsolete theory even more strongly 

 than would appear from his writings. We may, therefore, 

 confidently hope that further investigation and further 

 consideration will not fail to yield a satisfactory solution 

 of this interesting, if at present somewhat obscure, 

 problem. Yours faithfully, 



.J. LOUAN LoBLEY. 



THE PERIODICITY OF THE SOLAR SPOTS AND ITS 

 CAISE. 



To the Editor of Knowledge. 



Dear Sir, — Probably it is hardly necessary to say that 

 I am acquainted with Prof. Rudolf Wolf's labours on the 

 solar spots, and I am certainly not prepared to reject the 

 evidence he has brought forward of occasional irregularity 

 in their periodicity. But it seems to me that this is 

 perfectly consistent with my theory, that the periodicity of 

 spots, which has only been noticed during the present 

 century, is due to a swarm of meteors revolving round the 

 sun in an elliptic orbit, with a period equal to the average 

 period of the spots. Unquestionably, spots are also 

 produced in other ways, or by other bodies than this 

 supposed ring. Now these may sometimes come in a 

 considerable number a little after a time of regular maxi- 

 mum, which would protract that maximum, as in 1883 ; 

 or, on the other hand, near a time of regular minimum, 

 when they would cover and mask its occurrence. The 

 effect, indeed, would be somewhat similar to that of tidal 

 action in the Mediterranean, which can only be evidenced 

 by a long course of observation, being continually masked 

 to appearance by local causes of rise and fall connected 

 with the weather. Yours faithfully, 



Blackheath, W. T. Lynn. 



September 4th, 1894. 



[A meteor swarm which would, on its approach to peri- 

 helion, give rise to an appreciable solar tide, or to a 

 difference of pressure in the vapours beneath the photo- 

 sphere, would need to be of such mass that one would 

 expect to find some trace of its perturbing influence in the 

 motions of the planets ; and, in order to account for the 

 irregularities of Dr. Wolf's sunspot curve, we should need 

 to conceive of several such swarms, of considerable magni- 

 tude compared with the swarm which Mr. Lynn suggests 

 gives rise to the average length of sunspot periods. There 

 are not only considerable differences in the length of 

 successive sunspot periods, but the height of successive 

 waves of the sunspot curve varies, and the form of the 

 wave changes, groups of three or four similar waves or 

 loops of the sunspot curve occurring successively. Such 

 irregularities seem to me to point to complicated changes 

 taking place within the sun, rather than to a combination 

 of regular perturbations from without. Perhaps we shall 

 some day get an inkling of the meaning of such irregu- 

 larities, but I fear that we are very far at present from 

 understanding what a sunspot is. — A. C. Ranyakd.] 



