Oil Dry in o- and Prcscr 



'iin 



Sea- Weeds 



509 



cess is the same. The Sea-fir (Sertularia 

 Abiethia, fig. 4) will answer well, treated in 

 this manner. 



Some of the larger and heavier kinds, again, 

 may be afiixed to the card-board by narrow 

 bands of paper, gummed across their branches, 

 or strips of card-board inserted into incisions 



in the main piece. An infusion of gum- 

 mastic in spirits of turpentine, forms an ex- 

 cellent wash for some of the large coarse 

 specimens of Algte, and give them a 

 bright fresh appearance ; it must not be ap- 

 plied, however, until they are perfectly dry 

 and fixed. 



ON THE PHILOSOPHY OF BLUEING AND STARCHING LINEN 



IT is often worth while to think upon and 

 discuss those things v,hich are appa- 

 rently of small importance. The laws of 

 nature apply to small as well as to large oper- 

 ation, and the explanation of phenomenon of 

 great importance may frequently be found in 

 the investigation of trifling occurrences. 



Mr Ruskin, should this meet his eye, would 

 no doubt smile, while he would acknowledge 

 the truth of the statement, that the same 

 natural principles, by the observance of which 

 the great Turner (who he asserts was the only 

 artist who ever did paint water true to nature), 

 obtained his effects, include the one by which 

 a washerwoman makes a bosom assume a 

 whiteness of snowy purit}'. 



All tints are heightened by transmitted light. 

 No artificial pigments or dyes whatever can 

 approach the glory of the prismatic colours ; 

 but if artificial colours are laid upon a tran- 

 sparent surface, and light permitted to pass 

 through them, the effect of transmxitted light 

 will at once be seen. The stained windows 

 of churches are good illustrations of the in- 

 creased beauty of colour by the transmission 

 of light. 



The efiect of transparency may however be 

 produced in some degree by artificial means. 

 Light in passing through transparent substances 

 is more or less separated into its primary 

 colours by differences in thickness and density, 

 and the form of the surface. Moreover the 

 colour of the transparent body itself has effect 

 in the absorption of other colours, so that light 

 rarely passes through transparent bodies un- 

 changed. It took a long time to discover a 



means by which the dispersion of light, when 

 it passes through the lenses of optical instru ■ 

 ments, could be obviated, so that the image 

 presented to the eye should exhibit the colours 

 of the object inspected by their aid. It is 

 obvious, then, that if a tint be added to a colour 

 so delicately that the impression produced by 

 it does not change the original tint essentially, 

 something* of the effect produced by the 

 transmission of light will be attained. The 

 less of admixture with other colours any tint 

 possesses, the more easily will light be trans- 

 mitted through it, or perhaps it would be pro- 

 per to say, that unless the mixture be so per- 

 fectly compounded that a distinct new tint 

 is produced without a muddy cnide appear- 

 ance, the transmission of light will be more or 

 less interfered with. This perfect blending is 

 what is called by artists purity of tint. It is 

 seen in perfection ever\'where in nature, in 

 the clouds, in water, in flowers, leaves, and 

 fruit. 



An absolute white has a dead, dreary 

 appearance, caused by the utter absence of 

 the effect of transparency. It is, therefore, 

 rarely used in ornamental work unless it be so 

 placed as to be enriched by delicate reflec- 

 tions from adjacent objects. What is gene- 

 rally called a pure white has more or less of a 

 very delicate yellow, green, or blue tint, the 

 absence of which would be very sensibly felt, 

 although its presence, as a tint, is scarcely per- 

 ceived. This is why bhie'uig is used in the 

 starching of linen, though we venture to say 

 that the reason for it has rarely been thought 

 of sufficient importance to repay analysis. 



