1869.] CHEMISTRY AND PHYSICS, 111 



a very serious subject as regards the safety of both life and pro- 

 perty. I know not if any reliable observations have been made 

 in the matter, but the following ftcts were noted by myself some 

 years ago, and may throw some light upon the probable origin of 

 various terrible fires which have occurred on the premises of fire- 

 work-makers in London. Mixtures of the three ingredients — 

 nitrate of strontia (or barytes), sulphur, and chlorate of potash 

 — if made up at once from freshly and strongly desiccated mate- 

 rials, are certain to take fire spontaneously within a few hours, 

 especially if placed in a rather damp situation. The action, 

 which I twice had the patience to watch for and witness, begins 

 with the evolution of an orange-coloured gas; afterwards a 

 liquefaction is set up at several points in the mass; a hisi^ing 

 noise and a more rapid disengagement of the gaseous matter 

 comes on, and the composition takes fire. It is a curious thing 

 that the addition of a small proportion of sulphuret of antimony 

 at once prevents the occurrence of these phenomena ; whether 

 charcoal has the same effect I am not quite sure. Moreover, if 

 such compositions, being damp, are, in order to dry them, placed 

 00 near the source of heat, the same phenomena will take place 

 even when the antimony is used in their composition. Also, 

 compositions to produce a purple flame, if made with black oxide 

 of copper, are almost sure, sooner or later, to take fire of them- 

 selves at uncertain periods, whether kept in a damp or dry place. 

 The carbonate should always be used in preference. — R. Trevor 

 Clark." — Chemical News. 



New Chemical Toy. — "Pharoh's serpents" and "Vesuvian 

 tea" have paved the way for the reception of a new Chinese 

 wonder in the shape of "ferns growing out of burning paper.' 

 This is a neat little experiment free from many of the disadvan- 

 tages appertaining both to the "Devil's tears" and the lozenge- 

 shaped crystals of bichromate of ammonia, which may chance to 

 prove too inviting to children's tastes. The instructions direct 

 us to crimp or fold the yellow papers backwards and forwards, 

 so that when opened out they may be supported upright in a 

 zigzag form. One of these slips is then placed upright on a 

 plate, and ignited in two or three places along the upper edge, but 

 without being allowed to blaze. It will burn slowly down with a 

 red glow, diffusing an agreeable perfume, whilst the ash of the 

 paper assumes the most fantastic arborescent shapes, together 



