(24) Some machinery makers use a kind of thin black japan for preserving the brightness of polished parts. Some months ago the writer was in several works of Lancashire tool makers, and noticed this black material in use. It is easily laid on with a brush in the same way as paint, and is very readily removed at any time with a rag soaked in turpentine. It does not attack the metal, as the acid from fats is so liable to do, and has the great advantage of being much more cleanly both in use and appearance, being perfectly hard and dry, and thus allowing the machinery to be handled, which, in packing for railway transit or shipment, is very important. In many cases a great deal of the ordinary white-lead and tallow is rubbed off in the packing operations, and the object sought by its application is thus defeated. A good substitute for such mixture is very desirable, and the subject is worth the attention of engineers and machine makers. (T. T.)