

'"LATORY FORCES. LIGHT, [run OXY-HYDROOEX BLOWWPB. 



form. We (hull therefore, wo trust, bo not considered as 

 making an invidious selection, if we state, that as a 

 matter of choice we piv:,-r that illustrated in tin- annexed 

 engraving ; which is made and sold by Mr. J. J. Griffin, 

 ul liunhill-Mw, London. 



I n K; , l i, i represents the spirit-holder ; b is the wick- 

 holdcr, in which there are three tubes for separate wicks ; 

 Fig. 40. 



c is the tube which brings oxygen gas from the gas-bag, 

 the supply of the gas being regulated by the stopcock h ; 

 </ ia the jet by which the gas is directed into the flame of 

 the spirit-lamp, the wicks of wliit-h must be so arranged 

 that the gas does not strike upon the cotton and produce 

 a ragged flame, to which eud the wicks must be carefully 



I mi tho two sides; e is a wire for supporting the 

 lime cylinder, which ia shown apart by /; and 3 is a milled 

 head for turning the cylinder, so as to present different 

 sides of it to the action of the flame. The front end of 

 the apparatus is put bodily into the lantern, through an 

 opening madu tor that purpose in the back of the lantern. 

 The cylinders of lime, fixed at e, may easily be made by 

 tiling a piece of hard fresh-burut lime into a cylindrical 

 fiirm ; they may be about an inch long, and half an inch 

 in diameter. In using this arrangement the spirit-lamp 

 is first lit, and tho lime brought into its flame. This 

 drives oil' (he moisture which the lime always contains; 

 and which would cause it to split into pieces if it were 

 suddenly heated. The stopcock, h, is then opened, and 

 - is allowed to pass through the jet d, so as to 



tho flame on the lime cylinder. Weights should 

 bo placed on a board covering the gas-bag or bladder, 

 which may lay on the floor, and be connected with c by 

 means of uu india-rubber tube, A most beautiful white 

 light will lie thus obtained, which gives the excellent 

 results when applied to the magic lantern and similar 

 arrangements. Of course, the light may be kept up for 

 any length of time, by maintaining the supply of gas 

 through tho jet, and of spirit in the lamp. The lime 

 cylinder should be continually turned round, so as to 

 prevent it burning into holes, which would speedily 

 lessen the amount of light ; and sometimes might 

 throw back tho flame, and crack tho glasses of the con- 

 In using tho oxy-calcium light no danger of any kind 

 can arise ; and as such, it is eminently fit for home use. 

 This cannot be said of the next arrangement ; which 

 should never be employed except by those well ac- 

 i|ii.iintod with the risks which ara incurred. Despite an 

 experience of some years, and although from such wo 

 naturally have become careful during its employment, 

 we have had several accidents with the oxy-hydlOgBO 

 arrangement, which might have proved serious ; and 

 which, if occurring to inexperienced persons, would have 



-.;> Mtded in ntal re. suite. The force of our remarks 

 will be appreciated as the student peruses the following 



:|.tion of this apparatus. 



The oxy-hydrogon, or lime light, ia always employed 

 when large dnolving-Tiew lanterns are used ; and whilst 

 not so powerful or so pure as the electric light, 

 the advantages of constancy, steadiness, and greater 

 convenience of application. An intensely hot llamo is 

 produced by tho combustion of hydrogen or coal gas, 

 together with oxygen gas ; and for this purpose a peculiar 

 fonn of blowpipe is required, whose object is to keep the 

 two gases separate until tho moment of their com- 

 bustion. If this bo successfully done, all danger will bo 

 obviated : in the absence, however, of this precaution, 



:H 



>~r 



the most dangerous explosion will certainly ensue. We 

 shall not enter into a description of various kinds of 

 these blowpipes, but at once recommend that which we 

 prefer for our own use. (See Fig. 41). 



In tho annexed Fig. 41. 



engraving, H re- ft 

 presents tho pas- | t^ 

 sage by means of 

 which the hydro- 

 gen or coal gas 

 enters the blow- 

 pipe, and passing 

 on, it at last es- 

 capes at the jet. 

 O shows the op, 11- 

 ing by which the 

 oxygen gas enters 

 a pipe, which is 

 entirely isolated 

 from the hydrogen 

 compartment un- 

 til the two gases mix at the small orifice at the top 

 of the oxygen tube ; and tlus being near the mouth 

 of tho jot, prevents iiny previous admixture of tho two 

 gases. Stopcocks are attached to each tube to regulate 

 the supply of the gases, and tho cylinder of lime is 

 placed in front of the jet, as represented above. The 

 lime cylinder is almost always mounted on a pin con- 

 nected with clock-work, which, by its rotation, causes 

 ditfeient surfaces of the cylinder to be successively pre- 

 sented to the jot. 



In using the blowpipe, the following directions should 

 be carefully attended to, both as regards questions of 

 safety and success : 1st. To fill the bags with gases. The 

 oxygen bag may be filled as already described, for tho 

 oxy-calcium light. Caro should be taken always to use 

 the same bag for tho same g;is ; and never to employ tho 

 bag containing hydrogen loft from a previous exhibition 

 if a few hours have elapsed, lest any air may have 

 entered, and have so formed a dangerous and explosive 

 mixture. Tho student should always remember, that 

 both bladders and india rubber bags are porous; and 

 that gases have an astonishing tendency to mix together, 

 by what is called endosomic action. Coal gas is best 

 employed, ;is being easily obtained ; and the bag may be 

 filled by connecting it with an ordinary gas-pipe. Before 

 doing this the bag should be completely emptied of air, 

 by rolling it up and pressing it. It may then be loft to 

 expand by itself, through the pressure of the incoming 

 gas. Pure hydrogen may bo used ; and is produced by 

 adding one part of strong sulphuric acid to six parts of 

 water, which, when cool, should be poured on zinc 

 cuttings, or iron nails, contained in a stoneware or leaden 

 bottle. Water is thus ctoo ai posed, and its hydrogen 

 set free. The gas should be allowed to pass through a 

 bottle of water, to purify it,* before being received in 

 tho bag. This will prevent corrosion of the brass 

 and other metal parts of tho stopcocks and blowpipe. 

 2nd. In attaching the bags by the india-rubber pipes to 

 the blowpipe, care should bo taken that each should bo 

 atlixed to the proper connection. The hydrogen should 

 pass through that tube which surrounds the inner one 

 supplying oxygen; this is a matter of great importance. 

 Care should also bo taken to have all the connections 

 perfectly air-tight, or loss of gas, and risk pf explosion may 

 occur. 3rd. The hydrogen stopcock being opened, tho gas 

 should be lit, and allowed to 'bum gently on the lime 

 cylinder till it is quite dry. 4th. When this is done, 

 the light may bo produced by the hydrogen cock >>eing 

 first turned on full. The oxygen cock may then be 

 opened, and afterwards the supply of hydrogen dimin- 

 ished, until a full, brilliant, and white light is obtained. 

 The operator should always make it a rule to turn on the 

 luj<lrtjcH tap fully first, when /nn./itcing the light ; and 

 to turn off the rit when ho desires to ex- 



lit. It is also a safe precaution always to 

 have a little excess of hydrogen over the oxygen supply. 

 This slightly lessens the light, but adds to the safety u* 

 Set a*tr, p. 61, Fig. SSI. 



