September 20, 1889.] 



SCIENCE. 



201 



fluid holding in suspension numerous very minute brown globules 

 and a smaller proportion of lighter-colored larger globules. The 

 former are insoluble in water, but soluble in alcohol. The latter 

 dissolve in water. ' 



The raw lacquer is almost completely soluble in alcohol, ether, 

 carbon bisulphide, benzine, and solvents of gum-resins in general. 

 The most important and abundant constituent is urushic acid, 

 which occurs in the form of the minute spherules already men- 

 tioned. The acid is obtained by evaporating the alcoholic solution 

 to a sirupy liquid. The evaporation must be carried on over a 

 water-bath. If too much heat be applied, a tough, black, rubber- 

 like substance is obtained, which I found very troublesome to re- 

 move from the dish, and only strong nitric acid would affect it in 

 the slightest degree. 



As thus obtained, urushic acid is soluble in alcohol, chloroform, 

 etc., but quite insoluble in water. It possesses marked acid prop- 

 erties, turns litmus-paper red, and forms salts with metals. With 

 iron salts it forms a black compound, to which the color of the fine 

 ■ roiro lacquer is due. With plumbic acetate it yields a gray, floc- 

 culent precipitate. 



Although the drying, or rather the hardening, properties of lac- 

 quer are doubtless due to the oxidation of urushic acid, the prod- 

 uct extracted by alcohol possesses no drying qualities. This fact 

 was first observed by Professor Rein, in 1874. More recently 

 Korschelt and Yoshida have found that a peculiar albuminoid of 

 lacquer effects the drying by a diastatic or fermentive action. The 

 fact seems to be that the lacquer hardens only when the albumi- 

 nous substance is present. If heated above 60° C, or above the 

 temperature at which albumen coagulates, the lacquer will not dry. 

 The strongest evidence of the importance of the albuminoid to the 

 hardening process is found in the fact that while the urushic acid 

 will not dry by itself, it immediately hardens if a portion of the 

 unboiled gum and albumen that does not dissolve in alcohol be 

 added to it, and the rapidity of hardening depends upon the pro- 

 portion added. It is notable that the aluminoid does not lose its 

 peculiar property of effecting this oxidation by treatment with 

 alcohol. Besides urushic acid and the albuminoid, raw lacquer 

 contains a gum resembling gum arable, which doubtless imparts 

 some useful properties to the lacquer, and a volatile acid, to which 

 Professor Rein ascribes the poisonous effects of lacquer. 



We now come to the further preparation of lacquer for use in 

 the manufacture of the several varieties of lacquered articles, and- 

 I would say that whoever is sufficiently interested in the subject to 

 spend an hour at the National Museum will find the process of 

 manufacture very fully illustrated there. 



A portion of the raw lacquer, about sixteen pounds, is poured 

 into a large circular wooden vessel, and vigorously stirred with a 

 long-handled tool for five or six hours, while the heat of a small 

 charcoal -furnace is ingeniously thrown upon the surface to evapo- 

 rate the water. During the stirring, certain ingredients may be 

 added from time to time. The roiro, a fine black lacquer, is made 

 by adding iron at this stage. In Tokio a soluble salt of iron is 

 used, but the Osaka manufacturer objects to that, asserting that it 

 injures the quality of the lacquer. The material used in Osaka is 

 the fine iron dust collected from the grinding of knives. This is 

 added in quantities of about a teacupful of powder mixed with 

 water at a time, until the desired color is obtained. When the 

 work is finished, the lacquer is poured into a vessel to settle, and is 

 afterwards drawn off from the sediment. 



The wood generally used for lacquer-work is the light, easily 

 worked hinoki, a coniferous wood. It is prepared to receive the 

 lacquer in various ways. For inferior work it is first covered with 

 paper, but in the finer qualities paper is not used. The operations 

 to be described apply to the manufacture of that variety of lacque"- 

 known as Wakasa lacquer, and are from personal observation. 

 The wood is first carefully smoothed, and the corners of the boxes 

 strengthened by glumg pieces of cotton or hemp cloth around them 

 with raw lacquer. All joints and imperfections are then filled 

 with tsugi urushz {tsugz, " to fasten "), which fills like putty. This 

 is a dark-colored mixture composed of rice-flour made into a paste 

 with water, and mixed with seshime urushi. It soon hardens so 

 that it can scarcely be cut with a knife. Sometimes finely cut 

 hemp is mixed with the tsugi urushi. The work is then covered 



v^'x'Cfijinoko, a mixture of seshime urushi, and a coarse powder of a 

 yellowish color. The mixture is soft, of a yellowish-brown color , 

 changing to black by exposure to the air. It is spread with a 

 wooden instrument called hera. The article is left for a few days 

 in the open air to allow some of the water to evaporate, after 

 which it is placed in a moist-air closet to harden. In this way a 

 very hard, gritty surface is obtained, affording an excellent ground 

 for the succeeding coat. 



This process is not applied in making inferior goods. For these 

 a mixture of the powder with glue is sometimes used, and for this 

 reason cheap ware sometimes blisters when used with hot water, 

 the glue swelling if the water reaches it. Similar blistering may 

 also be occasioned by the natural gum of the lacquer if it should 

 be present in excessive quantity. 



The next process consists in covering the entire box with two 

 coats of lacquer, containing a finer powder known as tonoko, which 

 is a kind of ochre much used in Japan for cleaning and polishing. 

 This is likewise evenly spread with the hera. Three coats of this 

 are applied over the joints. The object of this process is to secure 

 an even, smooth-grained surface for subsequent work. The sur- 

 face is finally rubbed down with a kind of stone called toishi. 



The parts that are not to receive any decoration are now ready 

 for the finishing applications of lacquer. The other parts are next 

 cevered with a black lacquer, naka miiri urushi. The lacquer 

 used is shitaji urushi mixed with a kind of black lacquer known 

 as honkuro. probably the best kind of roiro lacquer. It is applied 

 with a brush, and requires to be rubbed down. 



Two coats of black lacquer are now applied. The first is roiro 

 put on with a broad brush. This dries with a brilliant reflecting 

 surface. When quite hard, the second application is made, and in 

 this, while s'ill soft, the designs are impressed. I use the word 

 " impressed " because in the Wakasa lacquer there is no painting 

 or drawing, but the figures are produced in a very curious man- 

 ner. The white decoration is applied by dropping egg-shell pow- 

 der in patches here and there. This is done very skilfully by 

 the hand. The other designs are made by pressing various forms 

 of leaves into the soft surface. Thus, the radiating or wheel-like 

 pattern is produced by so arranging the needle-like leaves of the 

 pine, the more complex leaf-pattern with the leaves of an ever- 

 green {Thuya orientalis), while many other effects are made by 

 scattering over the surface husks of rice, and these mingled with 

 very short pine needles. The mother-of-pearl from shells is also 

 used. The designs become more or less modified by the subse- 

 quent operations. 



The lacquer retains the impressions thus produced, when, after 

 the leaves, etc., have been embedded about a day, every thing ex- 

 cept the egg-shell powder and mother-of-pearl is removed. The 

 article is then put in the moist closet until it is thoroughly har- 

 dened, which may require ten days or a fortnight. The egg-shell is 

 in little heaps, the leaf impressions are beneath the general sur- 

 face. It is now necessary to fill up all depressions and once more 

 secure an even surface. The first step is to rub down the most 

 conspicuous projections until there is much less irregularity of sur- 

 face, but even after several successive coats of lacquer there will 

 remain some elevations and depressions. 



The next application is a transparent lacquer colored yellow 

 with arsenic sulphide. This is put on with a hake, and spread as 

 evenly as possible. The object of this is to afford a yellow ground 

 for the gold which is to follow. A thin coat of shiu-ai urushi is 

 spread over this, and the whole completely covered with gold leaf. 

 Then successive coats of the same lacquer, which is a transparent 

 red lacquer, are applied until the surface is quite even. The sur- 

 face then appears entirely black, beneath which all the gold and 

 decorations are concealed. 



Instead of a red ground, green is sometimes desired, as in green 

 lacquer. To make this, the shiu urushi is mixed with a green pig- 

 ment. The next operation is to rub down the surface with stone 

 toishi ox sai kido until the design is again visible. The pattern is 

 now revealed in gold with the pure white of the egg-shell powder 

 to relieve the effect. The work is finally rubbed with a special 

 kind of charcoal, which gives a perfect surface, but to rilake it more 

 brilliant it is covered with a finishing coat of fine lacquer. 



To make practical application of these remarks, I would say that 



