A naturalist in Western China : with vasculum, camera, and gun, being some account of eleven year's travel, exploration, and observation in the more remote parts of the flowery kingdom; . hardening copal varnish. In Chinait is applied only during cloudy weather when the atmosphereis surcharged with moisture or when a drizzle of rain is indoor work its drying is facilitated by hanging about therooms cloths saturated with water. The kind used on shipscontains Pei-yu in almost equal parts, and this mixturedries rapidly even in moderately dry, hot weather. How im-portant the knowledge
A naturalist in Western China : with vasculum, camera, and gun, being some account of eleven year's travel, exploration, and observation in the more remote parts of the flowery kingdom; . hardening copal varnish. In Chinait is applied only during cloudy weather when the atmosphereis surcharged with moisture or when a drizzle of rain is indoor work its drying is facilitated by hanging about therooms cloths saturated with water. The kind used on shipscontains Pei-yu in almost equal parts, and this mixturedries rapidly even in moderately dry, hot weather. How im-portant the knowledge of this peculiarity is may be gatheredfrom the following fact. Many years ago an experimentalconsignment of Ningpo varnish was received in was applied in the same way as ordinary copal varnish, infull sunlight and heat, with the result that it refused to harden,and remained tacky, and the failure resulted in its beingcondemned as worthless ! The only change which takes place in the composition ofthe lacquer in drying at ordinary temperatures is the slowabsorption of oxygen, finally amounting to 575 per cent, byweight of the original substance. Complete oxidation is found. THE LACQUER-VARNISH TREE (RHUS VERNICIFERA) -40 FT. TALL THE MORE IMPORTANT PLANT PRODUCTS 71 to be due to the action of a ferment, to which the name laccasehas been appHed, which is only active in a certain humidity ofthe atmosphere. Quite recently, however, the presence of aspecial ferment has been questioned, and the absorption ofoxygen attributed to an obscure chemical reaction depending onthe presence of a compound of manganese with a proteid-likesubstance. Chinese lacquer, in a raw state, unfortunatelypossesses properties which are poisonous to many people, pro-ducing swellings and eruptions of the skin in the same way asdoes its close ally, the Poison Ivy {Rhus Toxicodendron).Certain people are immune, but this property will probablyalways militate against its use in Western lands. Perhaps the
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1913
