Oct. 31, 1884.] 



♦ KNOWLEDGE 



561 



If a shower of 8i)arks, struck with flint and steel, is caught 

 on a sheet of i>aper, and the particles viewed as opaque 

 objects in a strong light, a numlier of bright metallic balls 

 will be seen. They are portions of steel melted by the 

 heat of the concussion, and they cause the timber to ignite. 



The first attempts to obtain a substitute for the tinder- 

 box by chemical means was made with matches like the 

 common lucifer, first dipped in brimstone, and then in a 

 mixture of chlorate of potash and lump-sugar. Chemists 

 used to sell them in square tiu receptacles, usually orna- 

 mented by washing the metal over with dilute nitric acid 

 to make it crystallise in fern-like patterns, and then covering 

 with a transparent varnish of gold or ruby tint. In front 

 of the match-holding part was a smaller compartment to 

 hold a little bottle, at the bottom of which was some 

 fibrous asbestos moistened with sulphuric acid. The match 

 was lit by bringing it in contact with the acid. 



The next plan was to make Prometheans, as they were 

 called, by rolling up in the end of a paper spill a tiny glass 

 vesicle containing sulphuric acid, and surrounding it with a 

 little lump sugar and chlorate of potash. A slight blow 

 broke the vesicle and ignited the preparation. These 

 things were neither cheap enough nor handy enough to 

 become popular, and they soon disappeared to give place to 

 deal matches, coated at their tips with brimstone overlaid 

 with chlorate of potash and sulphuret of antimony. These 

 could be ignited by drawing them briskly through a folded 

 card to which sharp sand was glued. Phosphorous matches 

 succeeded these, and for many years the sort in general use 

 was made at the cost of terrible injury to the workmen 

 making them, as continuous exposure to phosphorous 

 fumes causes disease of the jaw-bones and other evils. 



Phosphorous is one of those curious substances which 

 can exist in what are called allotropic states ; that is to 

 say, their molecules are capable of arrangement in different 

 patterns, with variations of their properties. Common 

 yello*ish-white semi-transparent phosphorous is highly 

 poisonous, as well as extremely inflammable. It can be 

 crystallised from its solutions. By keeping it melted in an 

 atmosphere of carbonic acid for many hours, it is turned 

 into red amorphous phosphorus, which is much less inflam- 

 mable ; does not flame at ordinary temperatures ; and does 

 not poison the workmen. There are other modes of pro- 

 ducing this condition ; and in one of its states phosphorus 

 is black. All the best makers now use the innocent 

 varieties of phosphorus for their matches, and the safety 

 kinds have the phosphorus on the black cards stuck on the 

 boxes, or supplied with them. Neither the match nor 

 the phosphorus in this state can be ignited by accident, but 

 when they meet with the excitement of friction, a quick 

 blaze is obtained. 



Although not belonging to match-lore, two interesting 

 substitutes for matches may be noticed in connection with 

 them. In 182-1 Professor Dubereiner discovered that 

 platina, in a finely-divided state, ignited a mixture of 

 hydrogen with oxygen, or common air, on coming in con- 

 tact with it. This gave rise to Dobereiner's lamp, still 

 seen in some chemists' windows. It consists, as now made, 

 of a small glass vessel inside a larger one. Hanging down 

 towards the bottom of the inside vessel is a piece of zinc. 

 Dilute sulphuric acid is put into the outer vessel, and rises 

 up in the inner one. The chemical action which ensues 

 evolves hydrogen, which fills the inner vessel, expelling the 

 dilute acid. On turning a stop-cock connected with the 

 hydrogen reservoir, the gas escapes and strikes against a 

 little ball of platina-sponge, which ignites it. As soon as 

 any gas goes out of the reservoir a fresh supply of dilute 

 acid enters, and again acts upon the zinc until enough gas 

 is given off to drive out the fluid and stop the process. 



This apparatus is so pretty and neat that it would, no 

 doubt, have been in much favour, but for the difliculty that 

 its action is very uncertain uidess the platina-sponge is new 

 and is perfectly clean. 



Yolta appears to have invented a lamp that bore his 

 name, atjd consisted in an apparatus for the production and 

 storage of a small quantity of hydrogen, which was lit on 

 its issue in a fine jet by an electric spark obtained from an 

 electrophorus. We recollect seeing one of these lamps 

 many years ago. It was in the form of a handsome 

 mahogany box, about fourteen inches high, with a little 

 brass dragon mouth for the flame to come out of. At the 

 bottom of the box was a drawer containing an electrophorus, 

 to be excited by striking it with a foxtail. The hydrogen 

 part of the apparatus was analogous to that of the Dober- 

 einer lamp. On turning a key the gas was allowed to 

 escape, and, at the same time, the electrophorus yielded its 

 spark. In a very dry country such a muchine would work 

 well, but in our damp one the electrophorus did not keep 

 its power. S. 



RAMBLES WITH A HAMMER. 



THE GEOLOGY OF CRICCIETH AND PWLLHELI. 

 By W. Jerome H.-vrrison, F.G.S. 



IT is, I regret to say, fully two years since the appear- 

 ance in Knowledge of my papers on the geology of 

 Llandudno and Rhyl. Still, the delay has not been with- 

 out its advantages, for it has enabled me to examine more 

 carefully the region which I am now about to describe — 

 Criccieth having been my headquarters for a few weeks 

 during the summer of 1883, and Pwllheli for a similar 

 period during the present year. 



Iloiv to Get There. — The two picturesque Welsh towns 

 whose names stand at the head of this article lie snugly 

 within the northern curve of Cardigan Bay. They are 

 well sheltered by hill ranges — mountains they may be 

 fairly called — on the east, west, and north, but the coast 

 slopes southwards to the sea, while the waves which lave 

 the shore can trace their parentage to the Gulf Stream. 



Criccieth is rapidly becoming fashionable. Artists found 

 it out long ago, and this year it has been crowded with 

 visitors. But Pwllheli, the termiuus of the Cambrian 

 Railway, is a typical Welsh town. It is rather hard on its 

 worthy inhabitants to wish that it may remain compara- 

 tively unknown and unvisited, yet there is a strong tempta- 

 tion for those who know it well to — keep their knowledge 

 to themselves. Travellers from the North or from the 

 Midlands will reach either town most expeditiously by 

 travelling through Chester to Bangor. From Bangor a 

 branch of the London and North- Western runs due south 

 to Atbnwen, a little junction where there are no houses. 

 Criccieth lies about four miles east of Afonwen, and 

 Pwllheli the same distance to the west, each forming stations 

 on the railway — the Cambrian — which encircles Cardigan 

 Bay. Another route is to travel by the Great Western 

 from Ruabon to Barmouth (through most lovely scenery), 

 and then northwards from Barmouth by the Cambrian line. 

 But, whatever route the traveller adopts, his ride will be a 

 long one if he proceeds direct from any of our great towns. 

 Yet is the long journey not without its compensation, for 

 the "cheap tripper" is left behind, and the negro minstrel 

 troubleth not. 



The Geologist's Equipment. — Let the man who means to 

 examine Welsh rocks provide himself with a stout pair of 

 thick-soled, wide-across-the-toes, lace-up boots ; a good 

 " shooting boot," with a feiv nails, answers well. Flannel, 

 next the skin of course, with a stout, dark, tweed suit. 



