Archceologia. 385 



is not changed by the first heating : but the second, and those which 

 follow, cause it to pass through various shades of green, until at 

 length it becomes yellow. The process is then complete, and the 

 graphitic acid obtained must be washed and dried in an exhausted 

 receiver, or at a temperature of 100° Centigrade. It is in the form 

 of very small transparent scales, which darken in the light : and is 

 insoluble, except in water or alcohol, which dissolve only a very 

 small amount of it. It may perhaps be used hereafter in photo- 

 graphy, as paper which has been dipped in its aqueous solution 

 becomes brown under the influence of light. 



Miscellaneous. — Action of Light on SulpTiuret of Lead. — It 

 has been observed that lead paint which has been darkened by the 

 sulphuretted hydrogen found in the atmosphere, etc., is completely 

 restored to its original whiteness by the action of light. The 

 bleaching is very rapid if drying oil, and still more so if boiled oil, 

 has been used in the paint. This fact proves how necessary it is 



that places where pictures are kept should be lightsome. Gun- 



Cotton and the Alkaline Metals. — Grun-cotton will explode if either 

 sodium or potassium is placed upon it ; but not if a mixture of 

 both. The discovery of these facts may perhaps lead to an expla- 

 nation of the effects which the alkalies are known to produce on 

 collodions. 



ARCfLEOLOGIA. 



The fear of the cattle plague has lately so much weighed upon all 

 classes of society, that it seems to have made itself felt even among 

 antiquaries, and the opening meeting of the session of the British 

 Archaeological Association, on Wednesday evening, Nov. 22, was 

 occupied by an amusing and interesting paper by the Hon. Secretary 

 of that body, Mr. H. Syer Cuming, " On Charms employed in Cattle 

 Disease." It would be an interesting, and far from an invaluable 

 labour, to trace the history of the murrains, or cattle diseases of 

 former days, and their causes and effects ; but Mr. Cuming has 

 treated only upon the means then employed for their cure, which, 

 being the mere results of popular superstition, have, of course, no 

 use in modern science and practice. Nevertheless, they furnish 

 curious illustrations of the state of knowledge and intellectual 

 development in the middle ages. The diseases of cattle were 

 ascribed, by the peasantry in those ages, and even in much more 

 modern times, to two agencies especially — to the malignity of cer- 

 tain classes of evil spirits, and to the influence of the evil eye. In 

 the process of cultivating the ground, he frequently picked up the 

 implements made of stone, which are now the object of so much 

 archaeological interest, but the real object of which the mediaeval 

 agriculturist could not understand, and he believed them to be 

 ungodly weapons which the evil spirits hurled at his cattle, and 

 which produced the dreaded and ruinous murrain. The fatal in- 

 VOL. VIII. — NO. V. CO 



