JONES, ON JAPANNIN6 AND VARNISHING. 33 



drop into it a small lump of potash, or pearlash, which hr.s been 

 hesited very hot over the fire, to expel its moisture, and which has 

 not afterwards been sutfered to become cold ; the vial is then to 

 be well shaken, and if the lump remains dry, or nearly so. the 

 alcohol is good, but if any considerable portion of it is dissolved, 

 it is unfit for use. 



Should the alcohol not prove good, it may be rectified, by put- 

 ting into the bottle in which it is contained, a considerable portion 

 of potash, prepared, and warm as before directed ; if there is much 

 water present, the potash ought to be equal in weight to one-third 

 of the alcohol ; on shaking the bottle, the water will dissolve the 

 potash, and this solution will fall to the bottom of the vessel, form- 

 ing two distinct liquids, as separate from each other as oil and wa- 

 ter ; after this has stood for some time, the alcohol must be care- 

 fully poured otF, and the same operation may be repeated. The 

 watery solution, and the lumps of potash, may be put into an iron 

 pot, and again dessiccated, when it will answer the same purpose,, 

 as well as at first. 



The above process, will leave the alcohol of a reddish color, of 

 which it may be deprived by distillation ; but this color is of no 

 consequence whatever in the making of ordinary varnishes, as it 

 will not give a sensible tinge, excepting to the lightest kinds. When 

 it is desired to deprive the alcohol of this color, and the means of 

 distilling it are not at hand, it may be accomplished by putting into 

 the spirit a small portion of calcined (or burnt) alum, the acid of 

 which will combinti with the potash, which will then fall to the 

 bottom. Should the alcohol still retain any coloring matter, it 

 may be rendered perfectly colorless, by filtration through fresh 

 burnt, pulverized charcoal. The method of doing this, and also a 

 simple apparatus, by which any one may accomplish its distillation, 

 will hereafter be described, for the sake of those who live at dis- 

 tance from large towns, and are unable to purchase it in a state of 

 purity. 



There is another mode of trying the strength of alcohol, and that 

 is by its spedjic graviti/^ or the weight of a certain bulk of it, com- 

 pared with the same bulk of water ; the greater its purity, the less 

 it weighs, and when perfectly pure, its weight is but little more 

 than four-fifths of that of water ; suppose, therefore, you have a 

 vial, which, when filled to a mark made on its neck, holds exactly 

 live ounces of water, the same vial, filled with alcohol, to the same 

 mark, ought (o coiilain but a small fraction more than four ounces. 

 The philosopher may require greater precision, but for the practi- 

 cal man the foregoing method is sufficiently coirect, atid may readi- 

 ly be employed. It is evident, that the size of the bottle is unim- 

 portant, provided the weight of the alcohol, which it will contain, 

 IS but little above four-fifths of the weight of its contents of water. 



On Lac, or Lacca. — Lac is a resinous substance, imported Irom 

 the East Indies, where it is found on several species of trees ; be- 

 ing deposited on the twigs by an insect, the coccus lacca. Lac is 

 brought to us in three states, known nndpr the denominations of 

 .5 Vol.. L 



