Aiigust 12, iSSo] 



NATURE- 



537 



Tables for the Analysis of a Simple Salt. By A. Vinter, 



ALA. (London: Longmans and Co., iSSo). 

 Many tables for the qualitative analysis of simple salts 

 already exist ; another set is just added to the list by Mr. 

 A. Vinter. It is very probable that students who — like 

 those for whom Mr. Vinter' s tables are arranged— can 

 only devote one hour a week to practical chemistry, 

 would do well to add that hour to those allotted to some 

 other study ; but if school-teachers will give their boys so 

 insignificant a smattering of practical chemistry, these 

 tables will, we think, be found useful and generally accu- 

 rate so far as they go, which is certainly but a very little 

 way indeed. 



LETTERS TO THE EDITOR 



[ The Editor does not hold himself responsilile for opinions expressed 

 by his correspondents. Neither can he unda-take to return, or 

 to correspond with the writers of, rejected manuscripts. No 

 notice is taken of anonymous communications. 



[ Tlie Editor urgently requests correspondents to keep their letters as 

 short as possible. The pressure on his space is so great that it 

 is impossible otherwise to ensure the appearance even of com- 

 munications containing interesting and novel facts. ^ 



The late Count L. F. de Pourtales 



Every naturalist must have noticed with regret the news of 

 the death of M. de Pourtales, of Cambridge, Mass., U.S., but 

 those who have had the pleasure of his friendship and who have 

 been fellow-labourers with him feel a most sincere sorrow at the 

 loss which science has sustained. 



The exploration of the deep sea brought Pourtales prominently 

 before the scientific world, and his practical knowledge of the 

 art of dredging not only produced results which were of great im- 

 portance to Alexander Agassiz and Lyman, but they also provided 

 him with a wonderful series of deep-sea corals, upon which he 

 laboured with great success. The floor of the Gulf Stream in 

 the Straits of Florida, the dredgings of the Hasslcr Expedition, 

 and lastly, the exammation of the results of the work done in the 

 Caribbean Sea during the voyage of the U.S. steamer Blake, gave 

 the opportunity, which was readily seized and utilised, of con- 

 tributing largely and thoroughly to the knowledge of the interesting 

 Madreporarian fauna of the depths. I can testify to the solid 

 merit of the work done by my friend, and I can never forget his 

 generous assistance, kindly criticisms, and desire to obtain the 

 perfect truth. He spared no pains, and was ever at work in the 

 difficult subject he especially chose ; and he speedily grasped the 

 relations of the past and present deep-sea coral faunas, and, 

 besides adding largely to our knowledge of forms, contributed in 

 a most important manner to the study of the generic and specific 

 value of certain structures. Of his knowledge of the Crinoidea 

 I need not write, but of the great value of the researches of the 

 grave, courteous, and most genial man who is no longer amongst 

 us I shall ever speak in terms of great admiration and gratitude. 



AtheuKum, August 8 P. Martin Dunc.\n 



The Recent Gas Explosion 



According to promise, I write to describe the continuation 

 of the experiments on the above subject. 



At present there is little else than failure to report, but as I 

 am leaving hom.e to-day and shall not be able to try any addi- 

 tional experiments for the next three or four weeks, I will merely 

 mention the results obtained. 



A piece of composition gas-pipe lOm. long, 15mm. internal 

 diameter, and 2 mm. thick, was filled with a mixture of 2 vols. 

 of hydrogen to I vol. of oxygen, and the gas exploded. The 

 tube was not affected, the cork which closed it being projected. 



It was then filled with a mixture of 10 volumes of coal-gas and 

 12 of oxygen, and in this case the tube withstood the explosion ; 

 a piece of india-rubber tube covered with calico tightly bound 

 round it, which was used to connect the farther end of the tube 

 to a metal stopcock, was however burst and the calico tom. 



To-day I tried a tube made of paper. The tube is 7 mm. in 

 diameter, and consists of eight layers of thin paper, ftuck to- 

 gether with paste, and varnished on the outside with shellac. 



This I have not succeeded in bursting with the mixture of 

 hydrogen and oxygen ; one of the caoutchouc stoppers which 

 closed the glass tubes cemented to the end of the paper tube 

 was blown off. 



I hope to repeat the experiment with another paper tube which 

 is not so strong. Herbert McLeod 



Cooper's Hill, August 9 



Heat of the Comstock Lode 



In May, 1S78, Jlr. Church, who was at that time Professor 

 of Mining at the University of Ohio, read a paper before the 

 American Institute of Mining Engineers on the heat of the 

 Comstock mines, which was subsequently, in an extended form, 

 included in the author's volume on the Comstock lode, of wdiich 

 a review appeared in Nature (vol. xxi. p. S''). 



In this paper Mr. Church states that the temperature of the 

 waters issuing from the mines worked upon the Comstock lode 

 has always been somewhat high, but it was not until they had 

 attained a very considerable depth below the surface that the 

 workmen first became inconvenienced by extraordinary heat. 

 At their present greatest depth (about 2,700 feet) water issues 

 from the rock at a temperature of 157° F. (70° C), and at least 

 4,200,000 tons of water are annually pumped from the workings 

 at a temperature of 135° F. Mr. Church estimates that to 

 elevate such a large volume of water from the mean tempera- 

 ture of the atmosphere to that which it attains in the mines 

 would require 47,700 tons of coal. In addition to this, he 

 calculates, 7,859 tons of coal would be required to supply the 

 heat absorbed by the air passing along the various shafts and 

 galleries through which it is diverted for the purposes of ventila- 

 tion. It follows that to develop the total amount of heat neces- 

 sary to raise the water and air circulating in these mines from 

 the mean temperature of the atmosphere to that which they 

 respectively attain, 55, 560 tons of coal, or 97,700 cords of 

 firewood would be annually required. 



Mr. Church, in his paper, quotes four analyses of waters from 

 the Comstock lode taken at different depths ; these vary some- 

 what as to the relative proportions of the various substances 

 present, but they contain on an average 42-62 grains of solid 

 matter to the gallon. Of this amount 2074 gi-ains are calcic 

 sulphate, I2'I3 grains carbonate of potassium, 4-85 grains 

 carbonate of sodium, and '66 grain of cVdoride of sodium. 



In order to ascertain approximately to what extent the produc- 

 tion of the large amount of heat absorbed by the water may be 

 ascribed to oxidation of sulphur and iron, the author first calcu- 

 lates the quantity which would be developed by the oxidation of 

 pyrites equivalent to the calcic sulphate in solution. But having 

 found that this amounts to only about j \ 5th part of that required, 

 he seeks another solution for the difficulty, and without any 

 calculations in support of the hypothesis, attributes this enormous 

 development of heat to the kaolinisation of felspar in the sub- 

 jacent rocks. 



In a communication to the Geological Society of London, 

 published in i\i€u Quarterly Journal, August 1879, entitled, "A 

 Contribution to the History of Mineral Veins," I endeavoured to 

 show that the kaolinisation of felspars is as inadequate to pro- 

 duce the effects observed as is the oxidation of pyrites, and a 

 recent paper read by Mr. Church before the American Institute 

 of Mining Engineers, as well as his letter on Subterranean Kao- 

 linisation'in last week's N.A.TURE, have been written whh a view 

 ofanswering these objections. 



In my communication to the Geological Society I apphed to 

 the kaolinisation of felspai-s a similar line of reasoning to that 

 adopted by Jlr. Church with regard to the oxidation of pyrites. 



The average proportion of alkalies contained in the rocks of 

 the di>trict i1 6-40 per cent., wdvde the mean of the published 

 analyses gives 11 '30 grains of alkalies in the U.S. gallon of 

 water. It follows that the 4,200,000 tons of water annually 

 pumped out must contain 813 tons of alkalies, and that, as 

 these are present in the rocks in the proportion of 6-40 per cent., 

 the felspar in 12,703 tons of rock must be annually kaolinised 

 and the alkaUes removed in solution. ,• ■ j 



The amount of rock in which the felspar has been kaolmised 

 being 12, 703 tons, and the number of tons of water pumped out of 



the min^s 4,200,000, it follows that ll252i^ = 330 is the num- 



^ 12,700 



her of tons of water heated by each ton of completely altered rock. 

 In order, therefore, that one ton of rock should be enabled to 

 heat 330 tons of water only 1° Fahr., and the specific heat of 

 these rocks be taken at -1477, that of blast-furnace slags, it would 

 require to be heated by the kaolinisation of its felspar to a tem- 

 perature above that of molten gold. Consequently to raise the 

 water 85°, or to a temperature of 135°, at which it issues, the 



