Chemical Science. '203 



5. Spontaneous Combustions. — The following case of spon- 

 taneous combustion has been described by Mr. James Gullan, 

 of Glasgow, see Edin. Phil. Journal, vol. vii. p. 219. Having 

 sold a respectable spirit-dealer a parcel of sample-bottles, I 

 sent them to hirn packed in an old basket, the bottom of which 

 was much broken ; to prevent the bottles from falling through, 

 I put across the bottom of the basket a piece of old packing- 

 sheet, which had lain long about an oil and colour ware- 

 house, and was besmeared with different kinds of vegetable 

 oil. About six or eight weeks after, the gentleman informed 

 me that my oily-cloth and basket had almost set his ware- 

 house on fire. The basket and cloth had been thrown be- 

 hind some spirit casks pretty much confined from the air, and 

 about mid-day he was alarmed by a smell of fire. Having 

 moved away the casks in the direction where the smoke issued, 

 he saw the basket and cloth in a blaze. This fact may give a 

 useful hint to persons in public works, where galipoli, rapeseed, 

 or linseed oils are used in their manufactures ; as it is an esta- 

 blished fact (though not generally known), that these vegetable 

 oils used in cloths, yarn, or wool, in the process of dyeing, and 

 confined for a time from the open air, are very apt to occasion 

 spontaneous fire, 



6» Polishing Poiuder from Charcoal — Mr. J. Thomson, of 

 Glasgow, has lately turned his attention to the property possessed 

 by charcoal of giving a fine polish when rubbed on metals. This 

 property is not possessed by charcoal in general, but has been 

 found to belong only to particular pieces ; no means were known 

 by which such charcoal could be distinguished, except actual trial, 

 nor was the cause of the superiority of some pieces over others at 

 all understood. Mr. Thomson, in consequence of information he 

 received from Messrs. Harts that the Dutch rush used in 

 polishing wood, owed its powers to silex, was induced to sup- 

 pose that charcoal made from wood growing on sandy soils 

 would have the property required, and on trial this was found 

 to be the case. It frequently happens that turners meet with wood 

 Vfhich very rapidly destroys the edges of their tools. Mr. Thom- 

 son procured some of this wood, and having converted it into 

 charcoal, tried its polishing powers. They gave great satisfac- 

 tion ; and hence Mr. T. recommends, that turners, cabinet- 

 makers, Sfc, should lay aside such wood when they meet with 

 it, as a source of charcoal for the copper-plate workers, Sfc, to 

 whom it is of more value than to the former, and who are con- 

 stantly in want of polishing charcoal-powder. 



7. On the colouring Matter of the Lobster. — M. Lassaignc has 

 lately examined the colouring matter of the lobster. He ob- 

 tained it by separating the shell of the animal from all other 



