1847.] Notice of Tremenheerite, a new carbonaceous mineral. 369 



should be again traced on that description of China paper commonly 

 used in Calcutta for lithographic purposes, with a medium pencil, or 

 better still in lake with a pen, and be then carefully rolled and packed 

 to prevent its being in the slightest degree crumpled or soiled ; equal care 

 must be observed whilst drawing, that neither greasy particles nor 

 perspiration touch the paper ; such drawings can be easily lithographed 

 even by indifferent native draftsmen, for all that remains to be done, is, 

 to apply the yellow transfer mixture over the pencil drawing, and when 

 ready for use the whole has merely to be drawn over (traced) with the 

 pen or brush and lithographic ink. Many of the plates of my Illus- 

 trations of Indian Architecture were prepared in this manner. The 

 outlines should be exactly of the depths required for the shading. 

 This plan is applicable to representations of any objects in outline and 

 for facsimiles of inscriptions in particular, and will be found much safer 

 than the actual drawings, with the chemical ink on the transfer paper, 

 which are always liable to injury and never certain of success. Drawing 

 the outline in pale red ink or lake is better than pencil, as the latter 

 being dark, is apt to be overlooked in the tracing. 



For drawing sculptures, &c. &c. a frame divided off into three inch 

 squares, "with thick white cotton twine well stiffened ; the centre per- 

 pendicular and horizontal thread being red for easier guidance, is strong- 

 ly recommended ; the paper must be divided also into squares. The 

 frame is placed at a convenient distance from the object, when all that 

 is requisite is to keep the same position whilst drawing, and this is 

 easily done by marking a dot on the object, cutting the crossing of the 

 red threads ; great accuracy and facility is attained by this method. 



It should be borne in mind that clear, bold outlines are far more 

 valuable than indistinct sketches, however beautifully colored, which 

 are indeed of little use. 



Notice of Tremenheerite, a neiv carbonaceous mineral, by Henry 

 Piddington, Curator Museum of Economic Geology. 



This substance was sent to the Museum from Tenasserim by Capt, 

 Tremenheere, B. E. as Black Wad, but it contains no trace of Manga- 

 nese. 



