342 



SCIENTIFIC MISCELLANEA. 



I^IGHT PRODUCED BY FrICTION AND CRYSTALLIZATION The light 



emitted during the attrition of some substances, such as quartz, has been 

 attributed to the intense heat which is produced by the friction ; a tempera- 

 ture sufficient, as is well known, to actually fiise the abraded particles. But 

 how are we to account for the luminous appearance of loaf sugar, or of tar- 

 taric acid, when broken — is the light electrical ? We can scarcely suppose 

 it to be so, when wet crystals of sulphate of potash are rendered luminous by 

 being shaken in a phial. Light is, also, emitted during the spontaneous frac- 

 ture of crystals in the act of crystallizing. If three or four gallons of a hot 

 solution of sulphate of soda be decomposed by carbonate of potash, and the 

 whole set aside in a dark place, during the crystallization of the sulphate of 

 potash, on the surface of the liquor the scintillations are so brilliant as to re- 

 semble particles of gunpowder, ignited by being thinly scattered upon a sur- 

 face of heated iron. E. W. B. 



Family Concerts — ^In most families in England where music is taught, 

 it is the custom for every individual, male and female, to receive instructions 

 on the piano, and each practises in separate rooms, or, at least, at different 

 times. If, instead of this, one were to learn the harp, another the piano, a 

 third the violin, and the rest the tenor, violincello, flute, &c., what delight- 

 ful concerts might take place within the family circle, and far greater plea- 

 sure would fall to the share cf both performers and listeners, from these 

 domestic concerts, than where each takes his solitary practice, to the great 

 annoyance, perhaps, of all the rest. There is, probably, nothing more pre- 

 judicial to the 'divine art' in P^ngland, than the prevailing custom of learn- 

 ing only the piano — and that but indifferently. If the organ and organ mu- 

 sic had the attention paid to them which they deserve, great improvement 

 might reasonably be expected. 



Colour produced in Organic Matter by Chlorine — It is well 

 known that chlorine destroys the colour of organic matter, but we were 

 scarcely prepared to find that it developes colour in some white organic sub- 

 stances. The wings of the whole of the white indigenous Butterflies, com- 

 prehended in Stephens' genus Pontla, are rendered, by chlorine, of a beauti- 

 ful deep pink colour. This effect is not produced by either muriatic or nitric 

 acids, neither does the experiment succeed with any of the other white lepi- 

 dopterous insects on which it has been tried. The colour developed on the 

 wings of P. rapcB, or the smail white, is deeper than upon those of the other 

 species ; and it is immaterial whether the insect has been lately captured, or 

 has been an ancient inmate of the cabinet. The experiment is readily tried 

 in the following manner ; — Attach the insect to a piece of cork fixed on the 

 inside of a tumbler, and invert the glass, for a minute or two, over a little 



