fan. 8, 1880] 



NATURE 



otheri. For showing the popular class-room experiment of 

 burning phosphorus in oxygen, I was in the habit of using a 

 little cup of chalk made deeper and with smaller rim than the 

 brass cups usually made for the purpose. The object of this 

 was to limit the too rapid outburst of combustion. I noticed 

 that a cup which had been used several times was coated on the 

 inside with a hard, glassy enamel, which I supposed to be 

 phosphate of lime. To test this, the cup was thrown into some 

 hydrochloric acid and dissolved bodily, but I found at the 

 bottom of the beaker an insoluble residue of crystalline particles. 

 What were these ? Could it be possible that the carbonic acid 

 driven off by heating the chalk had, on reaching the heated 

 phosphorus, become dissociated, its oxygen combining with the 

 phosphorus, and its carbon thrown down as veritable diamond? 

 To test this startling theory, I collected the particles and nibbed 

 them between a glass pestle and mortar. They appeared hard 

 enough to scratch the glass, but were too small for further ex- 

 amination. To obtain a better supply, I dissolved sonic phos- 

 phorus in bisulphide of carbon, pounded some chalk and 

 made it into a paste with the solution, then filled a porcelain 

 crucible with this and fired the mass by heating it over a I'unsen 

 burner. It blazed magnificently, throwing out eruptive jets of 

 flame. Here, in the absence of surrounding oxygen, the car- 

 bonic acid had every opportunity cf becoming di-sociated or 

 reduced by the heated phosphorus. The residue w as treated 

 with hydrochloric acid, and this time I found at the bottom of 

 the beaker quite a respectable quantity of crystalline grains. 

 These left unmistakable scratches on the glas - pe-tle and mortar, 

 and seemed to make some fine scratches on an agate pestle and 

 mortar. I next examined them under a micro- cope, and found 

 that they were more like pebbles than crystals, so much so as to 

 suggest another theory of their composition and origin, viz., that 

 they were miniature chalk flints formed by the fusion and aggre- 

 gation of the siliceous cuticles of fossil diatoms, or such-like 

 organismsof which chalk appears to be in some degree made up. 



To test this, I precipitated some pure carbonate of lime, 

 soaked it with the solution of phosphorus and fired as before, 

 then treated with hydrochloric acid ; when, alas ! my Eldorado 

 of dissociated carbonic dioxide melted into thin air as the effer- 

 vescent liquid gradually cleared traces of 

 crystalline residue. \V. Mattieu Williams 



^tonebridge Park, W'illesJen 



Solar Phenomenon 



On the afternoon of the iSth ult., in company with Ilerr 

 Lohse, of this observatory, I was occupied in adjust i.. 

 troscope attached to the 15-inch refractor. The sun was dis- 

 appearing behind the ridge of the hill of Fare, about five miles 

 distant. To utilise the last rays of the sun, I was directing the 

 telescope on the gradually lessening segment of the 

 while Ilerr Lohse was looking through the spectroscope. Under 

 these circumstances it will be understood that we were both 

 standing near the inner vertical surface of the drum-shaped 

 dome, close to where it was lit up by the sunlight coming 

 through the opposite vertical opening, which is 40 inches wide. 

 It may be well to add that the dome is made of corrugated iron, 

 painted slate-colour, the corrugations of the wall being vertical. 



Under the impression that the sun had wholly disappeared, I 

 looked at the inner wall of the dome to see if it was actually 

 shaded by the distant hill. 



To my great surprise, the still illuminated surface was crossed 

 by a number of distinct, horizontal, black lines, which ascended 

 at a uniform pace about a foot and a half in a second. The lines 

 were, on an average, about \ inch thick, while the intervals may 

 have been mostly some 2\ inches, but I do not think that the 

 intervals were uniform. Herr Lohse, on turning from the spec- 

 troscope, also saw the lines ; but while he feels sure 

 of them terminated in points, I am under the impression that all 

 the lines erased the entire illuminated space. 



The lines had a distinct quivering motion, which, combined 

 with their uniform ascent, gave the whole phenomenon a most 

 beautiful appearance. We both independently estin 

 number of lines seen at ab ut thirty, and the duration of the 

 phenomenon at half a minute from the time when we fir.-t saw it. 

 It was, however, certainly fully developed when first caught sight 

 of. These lines seem to be closely allied to those repeatedly 

 seen at the beginning or end of the total phase of a solar eclipse. 

 See particularly Astronomkche Nachrichten, Nos. 1,921 and 

 1,922, and " Le Soleil" (German edition), p. 301, et sfij. 



Some of the observers referred to speak of the lines as undu- 

 lating ; in this case it is difficult to say if the lines were quite 

 not, because of the corrugations of the surface on 

 which they were thrown. My own impression is that they were 

 straight except in so far as they were affected by the quivering 

 before mentioned. 



It would be remarkable indeed if this is the first time they 

 have been seen at the daily disappearance or reappearance of 

 the sun. Ralph Copeland 



The Observatory, Dunecht, Aberdeen, December 23, 1S79 



Carbon and Water Figures 



The separation of clear water from a uniformly diffused mix- 

 ture with soot is so remarkable that it seems worth attention, 

 especially in connection with the behaviour of charcoal powder 

 in water, which is always streaky after any amount of snaking. 



For some months I have observed and recorded tlic-e figures, 

 as shown in a large white basin of sooty rain water, which is left 

 undisturbed for twelve to twenty-four hours ; they only appear 

 occasionally, perhaps once in a week, are not constant when 

 formed, and are entirely destroyed by stirring or mixing the 

 water. They always consist of lines, planes, or patches of 

 dtarcr water, sometimes not containing certainly more than a 

 quarter of the proportion of soot around them ; no aggregation 

 of sooty water, or soot, has ever been seen. Tliese quasi- vertical 

 planes are very thin, sometimes the clearest part as little as J 3 th 

 inch wide, and the extreme thickness z ? s lh, the 

 being \ to 1 inch deep, and I to 5 long. Most usually only one 

 plane appears, the azimuth of which is quite irregular ; occa-i 

 sionally it is curved ; sometimes a row of quasi-parallel | 

 lines appear — once as many as six, at irregular intervals averaging 

 •8 inch; once a clear circular spot about 1 \ inch across 

 appeared. 



The last form I found was by far the most complex, and is 

 here given from a careful sketch. 



The lines were not as thin as usual, only one or two 

 little as „V inch wide. They were very bright, prol 



[ of the average soot around them; the water was 

 unusually dark. The central semicircular space was 3' 6 inches 

 long x 1 '7 inch ; when first seen this space was uniformly grey, but 

 in a few minutes, after slightly disturbing the water, the bright 

 sharp plane across it appeared, inclined at about 5" to vertical. 

 Some of the other planes were inclined 15 . The most striking 

 point was the sharp definition of the central space, all the lines 

 ending abruptly at its regular outline. 



The depth of these figures bears strongly on their cause. 

 They are never at the surface, but u ually on the bottom. The 

 water is about 2 inches deep, and the up] er limit of thc-e planes 

 is \ to i.j inch from the top, In the above figure the lines or 

 planes appeared to lie on the bottom, and to turn upwai 

 edge of the central space, leaving it untouched, thus forming a 

 bright edge to it. I have also, on disturbing wa 

 apparently that a clear layer existed below a uniforn I 

 surface. 



The conclusions are, th3t water tends to separate from the 

 finely divided carbon, in a clear bottom layer (or lines) of 

 uncertain thickness (though lamp-black sinks if diffused in 

 water), and that parts of this layer are (by convection?) turned 



