Januaby 5, 1900.] 



SGIENGE. 



33 



in Limestone County. The samples analyzed by 

 him contained from 15 to 20 per cent, of phos- 

 phoric acid up to 36 or 37 per cent. ; and he also 

 showed a sample of superphosphate prepared 

 by him from this rock, the manufactured article 

 containing 13.15 per cent, water — soluble, 0.15 

 per cent, reverted, and 1.24 per cent, in- 

 soluble ; total 14.9 per cent, phosphate. 



In the discussion which followed, Mr. Aid- 

 rich said that a fertilizer manufactory in Meri- 

 dian was using lignite from the Burning Cut in 

 Sumter County, Ala., as a filler, and that it 

 contained 1.5 to 2.0 per cent, ammonia. Mr. 

 Aldrich had formerly sold from the Blocton 

 mines several hundred tons of coal slack, to a 

 Shreveport company, for the same uses. He 

 also mentioned the fact that he had recently 

 examined a lignite occurring in Mississippi, 17 

 miles west of Starkville, which had only 4.5 

 per cent, of ash and which made a very good 

 coke. 



Dr. Smith then read a preliminary report of 

 the mineral statistics of Alabama for the second 

 and third quarters of the current year ; after 

 which, there being no other business before the 

 meeting, it was adjourned sine die. 



Eugene A. Smith, 



Secretary. 



DISCUSSION AND CORRESPONDENCE. 



DR. WILSON'S EEPLY TO HIS CRITICS. 



I CONSIDER it complimentary to an author 

 that his works should be criticised. It shows 

 that they are worthy of attention and consider- 

 ation. The friendly criticism in Science, De- 

 cember 22d,of my address delivered in Columbus 

 last August, before the Section of Anthropology 

 of the A. A. A. S., appears under such misap- 

 prehension as seems to require a word of expla- 

 nation. That address, as its title indicates, 

 was 'A History of the Beginnings of the Science 

 of Prehistoric Archaeology.' It was a resume 

 or description of the discoveries made, or alleged 

 to have been made, which led to the foundation 

 of the science, and a statement of the theories 

 advanced for its establishment. This being its 

 purpose, it was proper that I should treat of all 

 its topics, and this without binding me to an 

 approval of them. I was recording a history 

 of the science, not necessarily maintaining the 



truth of all the theories advanced by its found- 

 ers. The friend who wrote the criticism seems 

 not to have recognized the difference. He 

 makes strenuous opposition to the classifica- 

 tions of the science as set forth in my address ; 

 but none of them were mine. They had been 

 made in Europe many years since, were appli- 

 cable to that country, and most of them are still 

 in use there. In such a history as I was writing 

 it would have been highly objectionable for me 

 to have omitted them ; and so with most of 

 the other points in the criticism referred to. 

 Thomas Wilson. 



NOTES ON INORGANIC CHEMISTRY. 



An important practical application of the 

 liquefaction of hydrogen is that of the production 

 of high vacua, as described by Dewar in the 

 Proceedings of the Royal Society. At the boil- 

 ing point of hydrogen the vapor tension of air 

 is less than a millionth of an atmosphere, hence 

 when to vacuum tubes for the spectroscopic 

 examination of gases is attached a temporary 

 tube immersed in liquid hydrogen, the solidifi- 

 cation of the air in the tube produces a very 

 high vacuum. In this way the more volatile 

 constituents of atmosphere become concentrated 

 in the tube, and in numerous tests the presence 

 of neon and of helium was revealed in a volume 

 of air less than 50 cc. Some tubes showed a 

 hydrogen spectrum, but others did not, so that 

 the question as to whether free hydrogen exists 

 in the atmosphere cannot be considered as set- 

 tled. 



A LATER number of the Proceedings contains 

 a paper by T. G. Bonney on the parent-rock of 

 the South African diamonds. The ' blue 

 ground ' of the Newlands mines, which are 

 forty miles northwest of Kimberley, contains 

 rounded boulders of eclogite,and in this eclogite 

 are occasional colorless octahedra of diamond, 

 apparently as an original constituent. As the 

 eclogite boulders are water-worn, it follows 

 that the ' blue ground ' is not of igneous origin, 

 but it is true breccia produced by the destruc- 

 tion of various rocks, one of which — the eclogite 

 — has contributed the diamonds to the mixture. 



The analysis of a sample of Egyptian porce- 

 lain from Memphis is published by Le Chatelier 



