48 



SCIENCE. 



THE ^"D-LINES" SPECTRA.— ARE THEY DUE 

 TO WATER? 



By Lieut-Colonel W. A. Ross, late R. A. 



In the year 1834, Mr. Fox Talbot, F. R. S., attributed the 

 all but omnipresent rays affording the above-named spectra 

 to water, on account of its universality ; but the celebrated 

 experiment of Kirchoff has, since then, reversed that opin- 

 ion, and bestowed the power of emitting orange rays upon 

 sodium alone. 



Is it not more reasonable, however, to suppose that sod- 

 ium has more attraction for water than any other substance, 

 than to imagine sodium contained in every possible sub- 

 stance, from the eternally-burning Sun himself, down to 

 every particle of our atmosphere ? 



A man need not be a chemist, or pyrologist, to observe 

 that, if he holds in platinum tongs a fragment of marble, 

 or artificial carbonate of lime, or magnesia, before the blow- 

 pipe, a strong orange flame affording " D-lines " spectra is 

 emitted by the fragment, only so long as it is imperfectly cal- 

 cined, or, in other words, has lost its carbonic acid gas. 

 When calcination is complete, it begins to glow brightly, 

 and emits no colored " flame " at all. Let us call this orange 

 flame (a) in this case. According to modern chemical theo- 

 ries (a) can only be one of two things ; carbonic acid gas or 

 sodium. It cannot be carbonic acid, which so far from being 

 combustible, is used to " put out" flame. It can be proved 

 not to be sodium by making it impinge upon a bead of pure 

 transparent boric acid, in which it causes, after a time, 

 opalescence. This opalescence is removed by the similar im- 

 pingement upon the bead of an indubitable sodium orange 

 flame. Reasonable chemists, therefore, will not be inclined 

 to contradict Euclid that the same cause producing precisely 

 opposite effects is a rcductio ad absurdnm. Moreover, for 

 the supposed sodium to have been with the marble, and not 

 with the marble after calcination — " hie et ubique" like the 

 ghost of Hamlet's papa — is another absurdity, which no 

 modern chemist would require us to believe, although some 

 are very exacting if not always exact. May I hope that 

 most chemists will be now inclined to admit, first, that (a) 

 can be due neither to sodium nor to carbonic acid ; and 

 sacondly, that it must, therefore, be due to something else : 

 and this is the very impression that occurred to me after 

 thinking profoundly over the matter for several years. 



Indeed, I suggested to Mr. Hennessy, who was engaged 

 in making atmospheric observations at Mussooree, in 

 India, with a spectroscope belonging to the Royal Society — 

 and who was elected an F.R.S. for his pains — that the 

 " D-lines " were due to water, not sodium, so long ago as 

 1871, and he was very much struck by the suggestion. 



The methods I adopted to prove the truth (or improb- 

 ability) of the suspicion which thus arose in my mind were 

 as follows : 



1. —The whole of (a) in a weighed fragment of pure 

 marble was obtained by fusing it carefully before the blow- 

 pipe in a transparent bead of boric acid, when the carbonic 

 acid gas, which we may call (6), escaped in bubbles with 

 great effeivescence, (a) remaining behind as opalescence, 

 and the lime (c) combining with a portion of the boric acid 

 to form a ball contained in the bead — let us call the bead 

 ((/). I found the weight of the lime borate ball (c a) bore 

 the same relative proportion to that of the marble (a b c) 

 whether the latter had been previously calcined or not, so 

 that the opalescence in (d) could not possibly have been 

 part of (c) while (b) escaped in bubbles ; therefore the 

 opalescence must have been due to (a) or — 



( (ball) I 

 (a 6 c) + 2 (d)-{b) = ( (c d) S 

 { (hydrated boric acid) { 

 i {ad) \ 



I could not isolate (a) any further than this, because (a d) 

 or what I believed to be hydrated boric acid is, naturally, as 

 soluble in water as ordinary boric acid, so I tried — 



2. — Observing that platinum in considerable bulk also 

 produces (a) in a ratio increasing with the decrease of 

 temperature down to a dull red heat, I fused an ounce of 

 crystallised boric acid in an open platinum dish at red 



heat, and obtained a new kind of boric acid, which turns 

 brown with a strong resinous smell, on being ignited, like 

 that of burning sealing-wax, affords a slightly-oranged 

 "flame " — for the green pyrochrome of the boric acid over- 

 powers that of (a). — and forms an opalescent bead, which 

 reacts, as I believe, with much greater acidity before the 

 blowpipe than ordinary boric acid does. 



This I call platinised or hydrated boric acid, and shall be 

 happy to show it to any chemist who may consider the 

 matter to be sufficiently interesting. — English Mechanic. 



AN IMPORTANT DISCOVERY. 



A discovery in chemistry has just been published, which 

 bids fair to influence agriculture in a manner that may be 

 well described as revolutionary. It must soon compel the 

 attention of farmers and manufacturers of artificial manures 

 everywhere. The essential part which ammonia plays in 

 vegetation need not here be dwelt upon, and no one will 

 question the desirability of securing it cheaply and in quan- 

 tity. The importance of the recent feat of Messrs. Rick- 

 man & Thompson, of England, disclosing a plan by which 

 ammonium sulphate can be made and sold with profit at 

 two cents a pound, will not, therefore, be liable to be over- 

 estimated. The following account of the process is taken 

 from the Chemical A T e7vs : 



Within the last twenty years the manufacture of ammonia 

 synthetically has been several times attempted, and though 

 in every attempt it is probable that ammonia has been made, 

 it has never been produced on a commercial scale. In all 

 these attempts the process has been to combine the nitrogen 

 and hydrogen directly at a low temperature, and receive the 

 ammonia in solution in water, or by substitution, first form- 

 ing a cyanide at a higher heat, and then indirectly produc- 

 ing ammonia by the decomposition of the cyanide, the result 

 in both cases being ammonia in solution with water. Rick- 

 man & Thompson's procedure is altogether different, they 

 produce ammonium chloride direct, either in dry powder or 

 in solution, and this by the simplest and most inexpensive 

 means. Instead of employing retorts, as in all other places, 

 they merely use a closed brick furnace, the ash-pan of which 

 regulates the supply of air, and they cause the vapor of 

 water to be produced by the waste heat of the furnace itself. 

 With the exception of about a bushel of coke for starting 

 the furnace, the deoxidizing material and only fuel used is 

 coal-dust. The great difficulty in makingammoniafrom the 

 nascent hydrogen of water and the nitrogen of the air is the 

 restricted limits of temperature between generation and 

 decomposition, it being necessary that carbon, however used, 

 should be at a full red heat to decompose the vapor of water, 

 and at a bright-red heat to decompose ammonia. Now, 

 ammonium chl( ride under the same conditions is simply 

 volatilized and not decomposed. As chloride of sodium or 

 of calcium is decomp.sed at a full red heat in presence of 

 nascent ammonia, therefore one of these chlorides is mixed 

 with the eoal that ammonium chloride maybe formed; so 

 that if by chance the heat should be raised to a bright red, 

 no loss will be sustained — the ammonium chloride is simply 

 volatilized. By these means a greater range of working 

 temperature is obtained. At the present time, with the 

 consumption of from 20 to r8 lbs. of coal-dust and salt 

 mixed, from two or three lbs. of ammonium chloride is 

 formed. 



A New Audii'Hone. — Further experiments on the tim . 

 bre of musical instruments as rendered by the audiphone 

 have led me to the selection of the following as a distinct! 

 improvement on the birchwood veneer, both for musical 

 purposes and also for ordinary conversation. It has th< 

 same advantage as my previous form in not requiring to| 

 be held by the hand, it costs nothing, and requires n< 

 making. Take a sheet of stiff brown paper about 11 x 15I 

 inches, the paper being such as is ordinarily used for mak-l 

 ing up heavy parcels. Put the ends together, the middlel 

 forming a loop, and hold the ends between the teeth. The 

 paper must be pretty stiff, as the loop must stand oul 

 round and full, and of course the paper must be without! 

 folds or creases. Thomas Fletcher. 



