126 Dr. Clarke on the [August, 



fine music wire ; articles for which we are entirely indebted to 

 Germany. 



English brass also differs very considerably from Dutch brass 

 in its liability to become decomposed and rotten in the time of a 

 thaw, possibly from the combined action of cold and moisture, 

 as happened to a piano-forte making by my friend Mr. T. T. 

 Hawkins, the frame and strings of which were so exposed when 

 all those made of English brass wire broke, and the remains of 

 them were become quite brittle and rotten, and the broken parts 

 exhibited a dark coloured grain ; whilst all those which were 

 made of foreign brass wire remained unhurt. 



1 am, however, in hopes that this country will shortly be able 

 to rival the Nurenberg copper and brass : my father-in-law, Mr. 

 Wm. E. Sheffield, who has formerly been long in Germany, and 

 paid particular attention to these important objects, and is a 

 metallurgist of great skill and experience, having lately manu- 

 factured copper, zinc, and brass, equal in every respect to the best 

 foreign; and he is now endeavouring to establish a company for 

 the erecting of works on a large scale ; so that, I trust, this 

 country will not much longer remain under the stigma of being 

 excelled in some of its staple articles by the superior quality of 

 those of other nations. 



Another very important advantage resulting from Mr. Shef- 

 field's superior method of extracting pure zinc from its ores, is, 

 that he can employ ivith profit those poor ores, yielding much less 

 than 30 per cent, of metal, and which have hitherto been 

 rejected by the manufacturers of brass in this country to the 

 great loss of the miners. I am, Gentlemen, 



Your most obedient servant, 



Thomas Gill. 



Article XIII. 



On the colouring Constituent of Roses. In a Letter to the 

 Editors. By Edward Daniel Clarke, LL. D. Professor of 

 Mineralogy in the University of Cambridge, &c. 



GENTLEMEN, 



The doubts which have been entertained respecting the 

 colouring principle in flowers, and especially in the blossoms of 

 the rose, induced me to make a chemical examination of the 

 substance to which their colour is due. The use to which this co- 

 louring principle has been applied in the preparation of test paper 

 renders the inquiry v/orth a little attention ; and the inferences to 

 be deduced from it are such as may excite the curiosity of your 

 readers. Scheele succeeded in proving that the ashes of vege- 

 tables contain manganese, whence, perhaps, originated the 

 notion that the red colour of the radish and the green colour of 

 its leaves, were owing to the presence of this metal. With 



