432 PHILOSOPHICAL TRANSACTIONS. [aNNO ]7g4. 



solid, as the substance was before solution. Saturated solution of white lac in 

 alcohol spread upon paper, cloth, wood, &c. on evaporation left a thin coat of 

 resinous matter, which was not however bright and smooth ; and therefore this 

 solution did not afford a good varnish. 



IF. Experimenls to Decompound White Lac by Fire. 



Eight hundred grs. of purified white lac were put into a glass retort, to which 

 was affixed an adopter with a large bulb to receive condensed vapours, and the 

 hydropneumatic apparatus to collect elastic fluids, or gazes. There distilled over 

 204 grs. of yellow strongly empyreumatic oil of the consistence of butter, 400 

 grs. of thin oil which had the smell of tar, near 20 grs. of watery liquid con- 

 taining a little acid, perhaps the pyrotartareous or the sebacic acid ; besides 307 

 cubic inches of gaz. In the retort there remained 37 grs. of carbonaceous 

 matter, which was a pretty hard cinder, the under surface of which in contact 

 with the glass had seemingly undergone a partial fusion, and the glass itself to 

 which it adhered appeared to have been a little corroded. This distilled gaz con- 

 tained no oxygen to the test of nitrous gaz ; but 32 cubic inches of it were 

 absorbed by milk of lime, and near SQ cubic inches of it were absorbed by yellow 

 oxyd of lead, or massicot, placed in the focus of a lens ; during which absorption 

 lead was reduced, and water composed. The remainder of the gaz extinguished 

 flame, and was concluded to be nitrogen or azotic gaz. The gaz which was 

 obtained by distillation was therefore a mixture of carbonic acid, hydrogen, and 

 nitrogen gaz. This mixture burnt like what has been called heavy inflammable 

 air. The above 37 grs. of carbonaceous matter afforded 2 grs. of muriate of 

 soda, 1 gr. of carbonate of soda, 4 grs. of phosphate of soda. The lixiviated 

 carbonaceous matter being mixed with 300 grs. of red oxyd of lead, and exposed 

 to a due degree of fire, yielded about 60 cubic inches of carbonic acid gaz, and 

 a little regulus of lead ; but there was a residue of carbonaceous matter which 

 could not be burnt away in the fiercest fire in open vessels. This residue was 

 probably carbon, phosphoric acid, and soda, intimately mixed by fusion. 



From this analysis, it appears that 100 parts of while lac purified yield 



Butyraceous oil 25| . ^hen this experiment was made with unpu- 



Thiri oil 50 rifled white lac, the proportion of water and 



Water containing acid . 2i carbonaceous matter was much greater than in 



Carbonaceous matter, containing fo 



phosphoric acid, muriatic acid, the preceding experiments. On account also of 



and soda .... i\ ^j^g water, it was extremely difficult to prevent 



Carbonic acid, by estimation ....4 ' J ^ ^ ^ 



Hydrogen, by estimation \\ the substance boiling over and bursting the ves- 



Nitrogen or azote, by estimation lo" g^ig^ Charcoal of wood being mixed with white 



Deficiency by waste and error . . 2 lac, the oil seemed to distil over more readily. 

 Parts 100 \\\\\\ less water, and was paler coloured oil than 



