Dec. 1G, 1881.] 



KNOWLEDGE 



137 



EASY LESSONS IN BLOWPIPE CHEMISTRY. 



BT LlErTENAXT-COLOXEL W. A. RoS.>i, tATE R.A. 



I FEEL some difficulty in expressing the satisfaction experienced 

 by myself, in common, no donbt, with thonsands of others, at 

 seeing what has been for so long the great moral and intellectaal 

 deiiderattim of London — a cheap and simply-WTitten, but at the 

 same time thoronghly scientific magazine — so well supplied as it 

 promises to bo by Know-ledge ; and I beg, therefore, to offer you 

 ray humble efforts towards the accomplishment of this praisewortliy 

 object. First, if I have your permission, in tho simple exposition 

 of a scientific subject which has attracted my most ardent atten- 

 tion, and extracted evei-y leisure moment for its study, during the 

 last twenty-two years of my life ; secondly, by getting all the 

 working people I can in my neighbourhood to spend their spare 

 twopcnces weekly in tlic acquirement of Knowledge iu the way of 

 literature, instead of (as most do at present) in the purchase of 

 trashy penny and halfpenny novels, boiled-down Scott, police 

 richauffies, &c., &C. 



Lesson I. — How to Make a Blowpipe Axn Use It (Chemically). 



Many Englieli working young men already know how to use a 

 common month-blowpipe in soldering and goldsmithing, &c., so that 

 I shall have less difiieulty in explaining how very little more trouble 

 or pains are required in using it chemically. And first, as to 

 making a blowpipe. We all know that a common conical, or '' Black's 

 blowpipe" (invented by the celebrated Dr. Black, of Edinburgh), 

 made of tinned iron, with its brass nozzle, can be purchased for9d. ; 

 but I would strongly advise evei-y investor in 

 such nine pennyworth, to add to his blowpipe 

 a trumpet- mouthpiece (invented by the 

 German chemist, Plattner), which any wood- 

 turner will make of some hard-seasoned wood 

 for 2d. more. If, however, my young friend 

 is determined to make a blo^vjiipe for him- 

 self, I will now sliow him how to make a far more powerful in- 

 strument than the above, and one, also, which does not require any 

 art in blowing. A child can use it without being tanght ; indeed, 

 my little boy (age 7 years) has already done so. 



First, he must procure about a foot, in 2 in. pieces, of brass tubing, 

 half of which should be 7-10 in. iu diameter, and the other half a 

 little smaller, so as 'to draw in and out of the former like a tele- 

 scope, and yet fit air-tight. He must now solder a round piece of 

 brass into one end of the wider tube, so as to close that for ever. 

 These tubes are called the "Body-tubes" of the blowpipe. He 

 can then make the jet of a suiall brass tube, tapering to a point, 

 this form and xi:c. Two holes are now to be correctly bored through 



the sides of llie wider body-tube above mentioned, about i in. frotn 

 its closed end, so that this jet shall pass into them, closing air- 

 tightly the larger hole at a and the smaller at b, which places are 

 exactly 7-10 in. apart in the figiue. A smaller hole like that in the 

 figure is to be bored tlirough one side of the jet, between a and h. 

 A Ijrass nozzle, this shape and size, having a bore 

 tlie width of a good stout sewing-needle, is to be 

 fitted (but on no account screwed) on the tapering 

 end of the jet. A child's indiarubber air-balloon, 

 at the smallest size procurable, is tied ou the tliick end of the jet, 

 with waxed silk-thread, and this part of my j-oung friend's blowpipe 

 is complete. To complete the whole, all he has now to do is to 

 procure a wooden trumpet-mouthpiece to fit air-tightly into one end 

 of the smaller of the body -tubes above described ; but before fitting 

 it, he must fasten over the inner end of its bore a strip of oiled- 

 silk cloth, rather loosely, so that ;iii' blown upon the silk from the 

 outside shall pass into tho tube, but cannot pass back again into 

 the mouth. This silk, in fact, forms a simple valve. 



The young " pyrologist," or blowpipe-chemist, now possesses a 

 blowpipe which, with proper "re-agents," — cheap chemical sub- 

 stances with which to heat and treat his minerals, &c. — will on- 

 able him, after lie has been through a course of these lesson*, to 

 "analyse" — that is, take to (chemical) pieces, so as to show what 

 they are composed of — the "rocks" of the geologist or the 

 "stones" of the mineralogist, belonging to a whole continent, if 

 necessary (and if a decent time is allowed him for the purpose). 



The Editor vaU explain far better than I can, that everyone's eyes 

 see objects (small print, for instance) best at a certain distance. 

 This point is called their "focns," and this distance their "focal 

 distance." Most people's eyes hare not only a different focal dis- 



tance, but the focal distance of the same pair of eyes is apt (un- 

 happily !) to alter through age ; also in consequence of sickness 

 or accident. The telescopic form of this blowpipe (which was 

 invented by me about a year ago) enables each operator to draw it 

 out or shut" it up to the length suitable to the focus of his eyes. In 

 packing, he draws out the jet, and, folding its air-bag as closely as 

 possible, slips the whole into the smaller body -tube ; that, with its 

 contents, is passed into tUe wider body-tube, and tho whole shut up, 

 te!esco])e fashion, foiTuing a single short tube which can be carried 

 in the waistcoat pocket. 



In using the ordinary blowpipe, a little art is at first necessary, 

 wliich generally reciuires from one to three days' practice, according 

 to the capability of tho learner. The best way to acquire the re- 

 quisite proficiency I believe to be for tho student to sit down 

 with a lighted candle, having tho wick bent to one side, on a table 

 before him ; to take his blowpipe in the right hand, not gingerly 

 between three fingers, as some ivriters recommend, but firmly 

 grasped in the fist ; to apply the mouth-piece to his mouth with 

 his cheeks puffed out, and elbow on table ; to thus try to produce 

 from the candle-flame, a " iiyroeone," which is simply a cone ef 

 blue flame, breathing through his nose all the time. He will find 

 this quite easy, but after a time, the air, or rather breath, in his 

 cheeks will begin to fail, wlicu all he has to do is to pronounce the 

 word cow without opening his mouth. The effort to do this will 

 replenish his cheeks with air. 



HINTS TO LOCAL METEOROLOGICAL 

 OBSERVERS. 



(Reprinted, with the Author's permission, from Science Gossip.) 



I. H.U1ST0EMS. 



AS hailstorms are essentially local phenomena, it is to local 

 observers that we must look for any addition to our knowledge 

 of them. 



A reference to any Encyclopaedia article will show the sadly con- 

 fused state of our information on the subject. Flat contradictions 

 will be found on every page. It will be seen that while some 

 authorities assert that hailstorms occur most frequently in summer, 

 others maintain that winter is pre-eminently the hail season. There 

 must be an error somewhere. As a matter of fact, false statements 

 have been so persistently reiterated, that by mere repetition they 

 have come to be regarded as truths. 



Let me allude to one fertile source of eiTor. I have referred to 

 it before.* It is the confusion of hail proper, or French grele, and 

 winter hail, or gr^sil— -two entirely different phenomena. Orisil is 

 the small round powdery snow which often falls towards the end of 

 a snowstorm and in the early part of a very frosty night. I suspect 

 that Dalton and other observers did not distinguish between the two 

 kinds of hail, and spoiled their results in consequence. 



The following points are of prim.-iry importance, and should not 

 be overlooked in taking down an account of a hailstorm : — 



1. Penod.— The date and hour at which a hailstorm occurs, 

 though apparently small matters, are of the utmost importance. I 

 am inclined to think that while each country has distinct maximum 

 and minimum periods of hail-fall, the distribution of tho quantity 

 over tlie year varies materially. For example, in this cotmtry, the 

 maximum occurs in summer, and is verj^ strongly marked ; while in 

 Germany, the maximum is iu spring, and is not so decided. If the 

 periods of maxima and minima all over the world could be deter- 

 mined, a comparison of them would doubtless throw much light 

 upon the nature and cause of hailstones. 



2. Area. — When a Irailstorm is not purely local, it usually assumes 

 the form of the tornado, and sweej-s over the country in one, or 

 sometimes two, narrow bands. In the former ease, it is sufficient 

 to ascertain the area covered by the storm, but in the latter, it is 

 necessarj- to detei-mine («) the length, (b) breadth, (c) direction of 

 motion, and (d) rate of progression of the storm-band. Such par- 

 ticulars can only be obtjiined by the co-operation of numerous local 

 observers. Our organised observatories are quite incompetent for 

 such work, being too sparsely distributed over the country. 



3. Pht/Kical features of the localitij. — The proximity of mountains 

 seem to induce the fall of hail, while that of forests has the oppo- 

 site effect. Progressive storms often diverge from their course on 

 encountering a river or valley, aud follow that of tho depression. 

 It is therefore useful to note if any of those physical features be iu 

 the neighbotirhood of tho storm, and if so, their effect upon it. It 

 is also of importance, especially in the tropics, to determine the 

 elevation of the country above the sea level. It is frequently 

 asserted, on what authority I know not, that hail never falls in the 



* Mature, vol. xxiv. pp. 1S7-90. 



