CHAPTER VIII. 
Manufacture.—Part I. 
It is unnecessary to discuss here in detail the chemistry of lac. 
This subject has been dealt with very 
The chemistry of shellac. . ,, TT . .. 
fully by Tschirch (Die Harze und die 
Harzbehalter, pp. 812 — 830). See also Puran Singh’s note on the 
Chemistry and Trade Forms of Shellac, Forest Bulletin No 7. 
It will suffice to mention that shellac appears to be composed of a 
complex mixture of resin acids, resin esters and a wax. The resin 
acids are probably derived from hydroxy fatty acids. 
As is well known, shellac in storage gradually becomes less 
soluble in alcohol and it has been suggested by Puran Singh (loc. 
cit) who obtained the same results by heating shellac, that this 
change is due to the formation of either anhydrides or lactones. 
Puran Singh further states that the solubility of shellac can be 
restored by soaking in water for some days. The solubility of shellac 
is of the greatest importance to the manufacturer, and to the consumer 
who uses shellac in solution. Trade experience seems to indicate 
that the rate of decrease of solubility is proportionate to the area 
exposed to the air. Thus grain-lac becomes insoluble more rapidly 
than shellac, and shellac more rapidly than button-lac. One manu¬ 
facturer has stated that TN shellac loses 5 per cent, solubility per 
annum during the first three years, 10 per cent, during the next three 
years and 15 per cent, in subsequent years. 
The quality of shellac appears to depend very largely on the 
relative proportions of the resin and wax it contains. It has been 
definitely proved that the proportion of wax to resin in stick-lac is 
greater than in the shellac manufactured by the manual method (see 
Hatchett’s analyses quoted by Puran Singh—loc. cit.) and that the 
surplus wax is left in the kiri or residue. The alcohol processes 
presumably retain the whole of the wax in the shellac while other 
machine processes are believed to retain less wax in the shellac than 
does the manual method. This may be the explanation of the 
differences between hand-made and machine-made shellac and would 
indicate the lines on which research in this subject might take. The 
