Colouring Property vf the Oxide of Moljhdena., 15 



iandfcape the foliage of trees, Incrufting of the bark ; on cat- 

 tle, in reprefenting hair and wool ; the charadSier and folds of 

 drapery, the thinnefs of flower?, &c. &c. 



As well as the manual praftice, painting requires, i. A 

 boldnefs of hand in the dead-colouring: 2. In the fecond co- 

 louring, more circumfpeftion and labour : and, 3. Thorough 

 patience and attention in the retouching and finifhing of the 

 picture. Thefe qualities can no more be feparated than 

 Venus and the Graces. 



He who wiihes to infure himfelf a good manner of pencil- 

 ing {liould avoid copying fuch pifturos as are iniperfeft in 

 that refpecil ; for, if we begin with a flovenly or bad one, 

 every ftcp will plunge us deeper in error. But all attempts 

 at painting will be vain if we do not poflefs the power to 

 <letermine the form at once, which can only be acquired 

 through a previous praiilice in drawing ; for on this the clear- 

 nefs as well as the firmnefs of the penciling depends. 



There are two methods of preparing our pifture : one is, 

 to draw in the objeils with their ground colour, carefully 

 laying in the fliadows, dead-colouring the lights folid, and 

 prejerv'ing the jhado-zus tranfparent throughout the ivork ; ia 

 the fecond ftage, to correft the forms, and add to the darks 

 where wanted ; and, thirdly, after oiling out the parts, bring- 

 ing the whole into harmony by glazing, fcumbling, and 

 finifhing with the extreme lights and darks. This direclion 

 is genera! ; for, after the lights and darks are added, parts 

 may require to be kept down, enriched, &c., as practice mufi 

 direct. The fecond method is to dead-colour yiVif//;' through- 

 vut, and to finith the fliadows by glazing. The latter method 

 admits of greater changes being made in the work during its 

 progrefs than the former. 



*^* In our laft Efliiy, for W. Scope, read W. Scrope, 

 efq. of Caftle Comb. 



IV, Experiments on the Colouring atid Mordant Property of 

 the Oxide of Moljbdena. By M. i). Jakgku *. 



L IlESE experiments were made with foliated niolvbdena 



nf Altetiborg, in Saxony, prepared in the following manner: 



After haviinj; feparated the metal from ail quartzv parts, it 



was redn<-td into an acid by long expofure to a red heat iu 



.^u open crucible. This acid was then diil'olved in boiling 



' from bclierer's All^mehus Jouitiul tfer C/unh; Jarjuary IS^i. 



water, 



