150 ON THE VEGETATION OF PLANTS. 



Source of apprc- As copal is foluble in feveral of the efTential oils, it may be 



henhon. 'l he ex p e ft ec i that the application of thefe will do much injury to the 



will (often the writing. Such an expectation is well founded. If the writing 



drv comp ifiuon, be rubbed with a fmooth furface dipped in oil of lavender, 



cannot be eafily much of the colouring matter will be difengaged, and diftri- 



eradicated. buted more difFufely upon the paper ; but, as fome of it will 



have penetrated the interior parts of the paper along with the 



copal, it will be extremely difficult to obliterate the traces of 



the pen without the erafement being perceptible. This is the 



principal fource of apprehenfion, but I know of no method of 



Amber a proper obviating the danger. The perufal of a memoir on the nature 



co^bTufed' and P re P aration of drying oils > &c - b y Mr - Sheldrake (Philof- 

 Journal, 8vo. Vol. I. p. 259), fuggefts amber as a proper ar- 

 ticle for the compofition of ink, if enough of it can be diflblved 

 in any fluid fufficiently thin for the purpofe of writing. The 

 more difficulty there is in effecting thefblution of any tenacious 

 fubftance we ufe, the better, provided it can then be employed 

 without inconvenience. 



I am, Sir, 



Yours refpeclfully, 



WILLIAM CLOSE. 



II. 



Experiments and Ohfervations on the Vegetation of Plants, wkich 

 Jhevo that the common Opinion of the Amelioration, of the Au 

 f/iofphere, by Vegetation in Solar Light, is ill founded. By 

 James Wo odhouse, M. D. ProfeJJbr of Chemijlry 'in the 

 (Iniverfity of Pennfylvania, fyc. 



To Mr. NICHOLSON. 

 SIR, 



Pater N'ojier Row, May 27, 1802. 



Introductory J INCLOSE for the Philofophical Journal, the refults of va- 

 rious experiments, made in Philadelphia in the year 1801, up- 

 on the feeds, leaves, &c. of a variety of plants, which feem to 

 prove, that growing vegetables, contrary to an opinion almoft 

 univerfally adopted, do not purify atmofpherical air; and that, 



whenever 



letter. 



