Feb. 3, 1882.] 



• KNOWLEDGE ♦ 



303 



(Sunifsf. 



[219] — The Atomic Theort. — ^Vbere can I find the beat account 

 of the atomic theory, and whether any theory has been put for- 

 ward for the iusolabUity of certain substances in certain fluids ? — 

 Ernkst L. K. 



[220] — Chemical Analysis. — Could you inform me of the prices 

 of the best books on qualitative, quantitative, volumetric chemical 

 analysis, and food analysis ? — Ontvabd. 



[221] — Xatl'eal Philosopht. — Which is the best " History of 

 Philosophy" for students ? — A. Summeeso.v. 



[222] — Telepho.ve.— How could I construct a small telephone, 

 and how do you join the wire together, so not to interfere with 

 message sent ? — G. H. Moetimek. 



[223] — ^Anili.ve Dyes. — Could you kindly give me any information 

 on the nianui'acture of aniline dyes, or tell me where I can learn 

 anything about them ? — Ernest L. R. 



[221] — Electeical. — Would any kind reader of Knowledge inform 

 me how to make the '" rubber " for a cylindrical electrical machine ; 

 also whether it is necessary or not tliat the cylinder should be 

 covered with shellac varnish Y — A Greenock Student. 



[225] — Ivy Leaves. — Of the various common plants which grow 

 in these islands, ivy seems to me to show a wonderful variety of 

 leaf -forms, depending upon the locality in which it grows. I should 

 feel greatly obliged to any evolutionist who would explain the pro- 

 bable causes which produced thesa varieties. — E. C. E. — [The query 

 is accompanied by drawings of several varieties, but as they are 

 well known, it does not seem necessary to have the drawing en- 

 graved. We have sent it to Mr. Allen. — Ed.] 



[226] — Gravity. — Reading the leading article on p. 241, I am 

 quite at a loss to understand the following, taken from paragraph 

 four : — " The most careful observation of the planets' motions 

 reveals no evidence that gravity takes even any appreciable time at 

 all in traversing the spaces sepaiatLng the various members of the 

 solar system from each other." As we can never have any atom of 

 matter outside the influence of the gravitation of every other atom 

 in the universe, how can the velocity of this influence be mea- 

 sured ? 1 think It would be interesting to the readers of Know- 

 ledge if yon or some one would favour us with an article 

 eiplaining how this conclusion has been arrived at. — F. A. L. R. 

 [It can be shown that if gravity occupied a measurable time in 

 reaching a planet, there would be a force constantly hastening the 

 planet's motion. But the matter requires more space than can be 

 given in '■ Replies to Queries." — Ed.] 



[227] — B.ABOMETRic OSCILLATIONS. — Are wave-like oscillations of 

 the barometric column in gales matter of usual observation ? My 

 attention has only been lately attracted to the fact. When the 

 atmosphere is in a disturbed state during the passage of a cyclonic 

 system, I Bet the vernier of the barometer accurately, and watching 

 it closely for five or ten minutes, find that the coloran rises and 

 falls say the thousandth of an inch, or, if falling, jails by waves, 

 like the receding tide on the shore ; the intervals between the waves 

 being from thirty to sixty seconds or thereabouts. This may be a 

 fact known to all observers, but, being new to nie, I venture to ask 

 the question, and to solicit a physical explanation of these oscilla- 

 tions. — G. R. W. — [If you consider that a barometer indicates 

 atmospheric pressure, and that there must be waves of compression 

 and rarefaction during a storm, you will infer that the oscillation 

 yoa describe might have been expected. We do not know that it 

 has ever been specially noted before. — Ed.] 



ivrplifg to ©uerifS. 



[151] — Jordan Barometer. — -The inventor gives the sp. gr. of the 

 . glygerine as 12G at 60° F. (lide " ITie Glycerine Barometer," E. 

 Stanford, Charing^rross, London, price Is.). The glycerine em- 

 ployed is presumblv pure, as the above specific gravity corresponds 

 to the natural density of the liquid, as stated in Watts's 

 "Chemistri-." — Edina. 



[15.5] — Tortoise. — We kept a tortoise more than ten years. 

 V When he began to burrow for the winter (moving his body in a 

 rotatory manner) we put him in a wooden box without lid, with a 

 few Square inches of carpet over him, and stowed him away under 

 the sofa in the library. He was never deceived by premature fine 

 days in January or February, but when the true spring was coming, 

 he stood in the box on his hind legs, and with his fore-foot tapped 



to be let out, and we then turned him into the garden for the 

 summer. Ho became very tame, and I often held him up in the 

 open, and on speaking to him, " Come, Torty," he would put out his 

 head to have his poll rubbed. — Charles Few. 



[171] — CnoANlTEs. — Having examined many choanites polished 

 in the mass, and cut into thin sections so as to admit of the em- 

 ploj-ment of the microscope, and having compared them with the 

 living sea-anemones, I had come to the same conclusion as Prestcr 

 W., that the choanite is a silicitied sea-anemone. The structure of 

 the tubes is alike in both. — X. 



[171]— Choanites. — The answer given to the above query, at the 

 bottom of p. 231 of Knowledge, No. 12, is not satisfactory to me. 

 Probably your correspondent and I do not moan the same thing when 

 we speak of "Choanites." They differ widely from what we call 

 Alcyonites. He may see specimens of the fossil Choanite in the 

 British Museum, where they are described as " ailicified sponges, 

 from the chalk" and I think that those specimens show the spiral 

 worm round the cup, but, of course, both the worm and the cup are 

 in the fossil filled with coarse flint, and having been slit by the 

 lapidary, the former appears as spots of flint, as intersected on each 

 side by the wheel, and the latter as a straight, solid body of coarse 

 flint, with which the lateral tubes are connected. If the Choanite, 

 after all, is a sponge, as geologists say it is, it is easy to understand 

 how the worm maybe — I had almost said must be— a parasite. — 

 Yotir obedient servant, Prester W. 



[176] — The Blue Streaks in Brick Clay. — Theso are most pro- 

 bably disintegrated and decomposed sulphuret of iron, which is 

 abundant in the plastic clay. — X. 



[177] — Nactilcs. — The use of the gut running through the 

 chambers of the nautilus is to secure it to the first-fonne<i chamber 

 of the shell, as it has a periodical slipping of the muscle, which is 

 rei^eated thirty or forty times during the growth of the animal, 

 each time forming a transverse septum to resist the pressure from 

 without.— C. W. Oldfield. 



[185] — Cold Saturated Solutions. — Have you tried taking a 

 hot saturated solution of this salt, allowing to cool with constant 

 agitation, and then leaving it to stand over the night, at the tempe- 

 rature you want ? Evaporate carefully do^vn to dryness, without 

 spirting, a measured quantity, say 50 grammes (not CO) of the 

 solution, and weigh the residue ; the result, multiplied by 2, will 

 give per cent. — A Greenock Student. 



[193] — Action of Thundebsiorms.— Owing to the formation of 

 ozone, which acts as a powerful oxidising agent. Ozone is formed 

 by the passage of electricity through the atmosphere. — A Greenock 

 Student. 



[214] —Colours of Stamens. — I think T. Howse is scarcely fair 

 in testing Mr. Grant Allen's opinion as to the original colour of 

 flowers by plants grown in a conservatory, whose characteristics 

 are so much modified by cultivation. When one speaks of flowers 

 in a botanical sense, one means those grown in a natural state, 

 i.e., wild flowers. If T. Howse examines these, he will find not only 

 that with few exceptions the stamens are yellow, but, in a large 

 number of cases the corolla is yellow also, as buttercup, potcntilla, 

 dandelion, primrose, furze, &c. — F. D. H. 



Fermentation in Beee. — I see "F.C.S.," in reply to "In 

 Re" (p. 257), recommends him to read some work] on browing, 

 preferably Dr. Graham's lectures, "if published." Mayl be allowed 

 to state that they are published in the form of a pamphlet. I have 

 not my copy at hand, unfortunately, or would quote publishers. 

 Mav I also suggest that "In Re" read the articles, "Beer and 

 Brewing," in Urc's " Dictionarj- of Arts, Manufactures, and Mines" 

 (Longmans & Co.) and "Studies on Fermentation," by Pasteur 

 (English translation published by Lyon, 175, Strand, Lotidon) ? 

 " On Fermentation," by P. Schiitzenberger (International Scientific 

 Series, King & Co., London), is also well worth reading, but the 

 thanks of English brewers are due more especially to Dr. Graham. 

 — W. M. 



The limiting depth to which light penetrates in water was some 

 time ago stated to be 40 metres for Lake Leman, by Prof. Forel, 

 who used albumenised paper in his experiments. M. Asper has 

 recently made similar experiments on the Lake of Zurich by .i 

 slightly different method. He used the jihotographic plates called 

 etnuUioti plates (more sensitive than albumenised paper), and im- 

 mersed them during the night of Aug. 3, to depths of 'K>, 50, 60, 70, 

 80, and 90 metres. They were brought up after remaining twenty- 

 four hours in the water, and treated with oxalate of iron. All the 

 plates, without exception, were distinctly affected by the light. 

 Thus the chemical rays penetrate in clear water to at least 90 metres 

 deep. — Scietitijic American. 



