510 Sir G. C. Haughton on the Common Nature of 



Amethyst with M 65^ \ PI. 90% difficult; Cad. 90' x; 



T 90°x. 

 Opal with M failed; Cad. 90" + ; T 90° + . 

 Cornelian (red) with M '35^; I 90°, f. very strong; P.G. 90°, 



f. strong ; T 90°, f. strong ; Z 90°, f, strong ; Cop. 90°, 



f. strong; Gl. 90°, f. very easy and strong. 

 Cornelian (white) with M 37°; I 90°, W easy; P. G. 90°, 



f. strong ; T 90°, f. strong ; Z 90°, f. strong ; Cop. 90°, 



f. strong ; Gl. 90°, f. very easy and strong. 

 Blood-stone with M 37° ; I 90°, f. very easy; P. G. 90°, 



f. very strong ; T 90°, f. strong ; Z 90°, i\ strong ; Cop. 90°, 



f. strong; Gl. 90°, f. very easy and strong. 

 Quartz with M 90° ; PI. 90°, very easy ; T 90°, f. strong ; 



Cop. 90°, f. easy; B 90°, f. firm. 

 Flint with M 90°; I 90°, very difficult; P. G. 90°, f. ; PI. 



90°, not very firm; Cad. 90°; T 45° ; L 90°, f. easy; 



B 90°, f. ; Gl. 90°, f. very strong. 



This class has been tested but to a limited extent with non- 

 ferruginous needles, but the results are sufficiently plain to 

 prove that they follow the same law as the preceding classes, 

 and there can be no doubt from the indications afforded by 

 what have been tried, that they would have exhibited those 

 strong affinities, belonging to all substances of the vitreous 

 class. A second specimen of diamond, which was a mere 

 spark, was tested witli the magnet and iron, but the results 

 were the same as with the first specimen. I am indebted 

 for many of these specimens, to Messrs. Widdowson and 

 Veale of the Strand, who very obligingly afforded me the use 

 of them. 



4M Class. 



Flint glass (prism, English) with M 30°; P. G. 90°, f.; G 1 8c. 



73°, difficult ; P 90°, f. ; PL 90°, f. ; Cad. 90°, f. ; T 90°, f. ; 



L 90°, f. ; Z 90°, f. ; Cop. 90°, f. ; B 90°, f. ; Gl. 90°, f. 

 Flint glass (tumbler) with M 90°+ ; I 90°, f. ; P. G. 90°, f. ; 



G 18c. 90° ; P 90°, f . ; PI. 90°, f. ; Cad. 90°, f. ; T 90°, f. ; 



L 90°, f. ; Z 90°, f. ; Cop. 90°, f. ; B. 90°, f. ; Gl. 90°, f. 

 Crown glass with M 90° ; I 90°, f. very easy and strong ; 



P. G. 90°, f. not easy; G 18c. 90°, very easy ; P 90°, f. ; 



PI. 90°, f. ; Cad. 90°, f. ; T 90°, f. ; L 90°, f. ; Z 90°, f. ; 



Cop. 90°, f. ; B 90°, f. ; Ars. 90°, f. most easy. 

 Blue glass with M 90° + ; I 90°, f. ; P. G. 90° + ; G 18c. 85°; 



P 90°, f.; PI. 90°, f.; Cad. 90°, f.; T 90°, f. ; L 90°, f.; Z 90°, 



f.; Cop. 90°, f. ; B 90°, f. ; Germ. S. 90°; Gl. 90% f. 

 Green fancy glass with M 90° ; I failed ; P. G. 90°, f. ; 



G 18c. 70° ; P. 90°, f. ; PI. 90°, f. ; Cad. 90°, f. ; T 90°, f. ; 



