SCIENCE. 



517 



be raised to the fusing-point, so that, although small por- 

 tions of almost every other metal or alloy could be readily 

 fused upon it, even the most fusible, such as antimony, 

 bismuth, &c, could not be made to combine with the 

 aluminium. 



As I had then studied blowpipe analysis on the Frei- 

 berg system for ten years, it was obvious lo me that, al- 

 though I had no chance of otaining the ^1000, the facts 

 thus ascertained might be utilized so as to make alumin- 

 num plate or foil remedy in par:, at all events, the disad- 

 vantages above described of charcoal as a blowpipe sup- 

 port. 



1 found that arsenic, antimony, bismuth, &c., the fusion 

 of the smallest particle of which upon platinum is so fatal 

 to it. could be treated without the slightest danger before 

 the blowpipe upon aluminium, which metal also, probably 

 from the reason above given, withstood heat concentrated 

 upon any point, in direct proportion to the bulk of the 

 fragment used as a support. 



I found that some volatile metals, as e. g. t antimony, 

 would not yield a sublimate when treated before the 

 blowpipe upon the bare aluminium plate, but readily did 

 so when a small slip or lozenge of charcoal was placed 

 between the assay and the aluminium. Here, then, was 

 a rapid and effectual means of separating the pyi oxides 

 or sublimates obtainable from a compound, for instance, 

 of antimony and arsenic ; the latter subliming readily 

 upon the bare aluminium plate; the former only after 

 treatment upon a charcoal slip. 



The horizontal charcoal support was, of course, 

 changed into a perpendicular one, in direct opposition to 

 the blast from the blowpipe, so as to catch all sublimates 

 of every kind; the grey-colored, shining aluminium be- 

 trayed at once the faintest sublimates, whether black or 

 white ; these, again, could be readily treated by the ox- 

 idizing or reducing flame of the blowpipe on the alumin- 

 ium, where they thus afforded, in most cases, new and 

 characteristic reactions ; the perpendicular aluminium 

 could be graduated by a scale showing the different spec- 

 ific gravities of sublimates by their mean ascension on 

 the plate, unacted upon by the blast as in the case of 

 charcoal ; and finally, any portion of a sublimate could 

 be easily and cleanly scraped off with a penknife, so as to 

 be afterwards examined in any way desired. 



Another advantage I found, referrable, I presume, to 

 the same cause (of superior heat-conduction in the sup- 

 port) is that the alkaline carbonates, so often used in 

 blowpipe analysis, as in the detection of manganese, for 

 instance, assume, when treated before the blowpipe on 

 aluminium, a globular shape, and that the resulting bead 

 or ball of sodium or potassium carbonate, can be readily 

 picked, when cool, off the plate with forceps, instead of 

 lying in a kind of pool and sticking to the metal as they 

 do in the case of platinum foil. 



To other uses of aluminium plates, as in flattening 

 blowpipe beads and their contents for microscopical pur- 

 poses, I have not time to allude. 



(2) A NEW AIR-RESERVOIR MOUTH BLOWPIPE (CALLED 

 BY ME A "PYROGENE.") 



A member of the Royal Geological Survey of England 

 told me in Jermyn street, that he believed many geolo- 

 gists and mineralogists were deterred from using this 

 important little instrument by the trouble if not difficulty 

 of blowing, and for a long time I tried to discover some 

 means of obviating this difficulty in vain. At last, one 

 day, in the Zoological Gardens of London, looking re- 

 flectively at the antics of some anthropoid types of our 

 ancestors there, I could not help feeling a kind of regret 

 that the process of "Natural Selection" should have 

 eventually deprived my race of the pouch under the jaw, 

 no doubt at one time possessed by them, which would 

 have served so admirably as an air-reservoir in using the 

 blowpipe, and it suddenly struck me that I could partially 

 remedy the defects of specific development in this matter, 



by applying an elastic air-reservoir of indiarubber to the 

 ordinary mouth-blowpipe. 



Here is the result. I have made it of a simple tube- 

 like form, instead of the usual tapering one, as seen in 

 Black's blowpipe, because I had to adapt it to be packed 

 in a cigar-case like this, the only way of effecting which 

 was to have it in a telescopic arrangement, opening and 

 shutting thus : and this arrangement had another 

 advantage, that, namely, of adapting the length of the 

 instrument to the differing optical focus of differing 

 vision. 



For the jet I took Wollaston's ingenious idea of pass- 

 ing the stem of the blowpipe through the aim of the jet ; 

 only instead of doing that, it suited my purpose better to 

 pass the jet through the stem of the blowpipe thus. Of 

 course, in either case, the inserted tube must fit air-tight 

 — an easy matter to effect. Over the throat of the mouth- 

 piece is tied a piece of oiled silk, which acts as a valve, 

 preventing the return of the breath into the cheeks. In 

 this manner all difficulty in blowing is entirely removed, 

 and even a child can use this blowpipe, because all he 

 has to do is to blow through the valve till the air-bag is 

 filled; then he can stop until the pressure of the blast 

 begins to slacken, when a few more breathings will refill 

 the bag. The blast pressure from the bag may also be 

 increased by the operator placing it between himself and 

 the table, and gently pressing the bag with his body, 

 which he can easily do while using this apparatus. 



I have only to add that, as you observe, the jet and 

 air-bag fit for packing into the tube of the blowpipe it- 

 self, for which purpose there is no necessity, as in the 

 one I have here, to make the end screw off, as all one has 

 to do is to draw the telescopic arrangement out alto- 

 gether, and, slipping in the jet and bag, to shut it up 

 again ; this, of course, would make the article cheaper. 

 Griffin makes them (with the screw end) for, I believe, 

 half a ctown, but, of course, any ordinary mechanic 

 could make such a blowpipe for himself for a few pence. 



(3) THE PYROLOGICAL CANDLE. 



I begin a brief description of this fuel with the remark 

 that it is practically impossible for the traveller to use 

 gas of any kind — not even petroleum gas — as fuel, on 

 account ot the difficulties of carriage. _The same re- 

 mark applies, but in another way, to oil of any descrip- 

 tion. A bottle of this is no doubt, easily carried, but is 

 very apt to leak at the cork, and so to spoil any or most 

 articles near it in a box. 



Considerations of this kind led me, in 1871, to look to 

 the modern composite candle as a substitute for the Ber- 

 zelius blowpipe lamp, supplied with Plattner's Freiberg 

 apparatus, which I had used for twelve years. The can- 

 dles then used for blow-pipe operations were, indeed, in 

 no respect different from those used for illuminating pur- 

 poses. How Von Engestrdm, Bergmann, and the more 

 modern pyrologists who are said to still use common can- 

 dles for blowpipe work, contrived to do anything useful 

 with them, I fail to understand. With even a small wick 

 in the centre of the candle, which, of course, must be 

 turned on one side to prevent it from stopping the blast, 

 the heat radiation from the blowpipe-pyrocone melts the 

 tallow or wax from that side more rapidly than the re- 

 mainder of the circumference melts, so that a deep chan- 

 nel is soon formed, down which the fluid fuel runs, 

 leaving the wick " high and dry." The consequence is 

 that the pyrocone becomes " thready," from the burn- 

 ing of dry carbonaceous particles eliminated from the 

 wick, and when it is cut down a mass of unconsumed 

 tallow almost covers it at one side. 



I therefore adopted the plan of having the candle made 

 with a thick, and even double, wick, placed at one side 

 instead of in the middle of the fuel, and in order to sup- 

 ply more of the latter, I had my candles made a pris- 

 matic instead of a round shape. I placed a thick collar 

 of a good conducting metal, such as zinc, round the 



