MECHANICS AND USEFUL ARTS. 119 



HIGH-PRESSURE CONVERTER. 



Mr. Bessemer has patented a method of conducting his pro- 

 cess under pressure, by means of which sufficient heat is pro- 

 duced to retain complete fluidity in the steel until it is poured 

 into moulds. For this purpose he makes the converting vessel 

 of great strength and as air-tight as possible, and makes the 

 mouth of it circular instead of oval, and of smaller size than 

 usual, lining this mouth with a ring of well-burnt fire-clay or a 

 composition of clay and plumbago. Mr. Bessemer states that 

 for the conversion of the purer kinds of Swedish charcoal pig 

 iron and for mottled or white hematite pig iron mixed with gray, 

 a back pressure in the vessel of from 8 to 15 pounds on the 

 square inch will give good results, and in but a few cases will a 

 pressure of 20 pounds per square inch be necessary ; while a 

 pressure as low as 3 or 4 pounds will be of little practical 

 advantage, and below 2 pounds per square inch he lays no claim 

 to a useful effect. 



MAGIC-LANTERN PICTURES ON GELATINE BY A NEW METHOD. 



At the last meeting of the Franklin Institute, the Resident Sec- 

 retary, Prof. Morton, exhibited in the lantern some pictures on 

 gelatine, prepared in a manner devised by Mr. Shepherd Hoi- 

 man, ti member of the Institute. 



For this purpose, a sheet of gelatine, such as is used for tracing 

 by engravers, was securely fixed over an engraving, and with a 

 sharp steel point (made by grinding down the end of a small, 

 round file), the lines of the original traced pretty deeply on the 

 transparent substance. Lead-pencil or crayon dust was then 

 lightly rubbed in with the finger, and the picture was at once 

 ready for use. 



A number of such drawings could be easily carried between 

 the leaves of a book, could each in succession be placed in a 

 frame or cell made of two plates of glass supported by a frame 

 of thin card of three edges, and united by paper or muslin pasted 

 around the same edges. The effect of these drawings in the lan- 

 tern was excellent, and their ease of production very great. 



PAPER FROM OAT-HUSKS. 



W. Hay, of Glasgow, Scotland, has just patented the following 

 process. He first immerses the oat-husks in water, in a tank or 

 other convenient vessel, in order to float off mustard and other 

 seeds with which they are generally more or less mixed, and 

 which, if not separated, materially deteriorate the quality of the 

 paper. It is of advantage to have the water well stirred, as it 

 facilitates the separation of the foreign seeds, and allows them to 

 float to the surface. The oat-husks are then allowed to settle, 

 and the surface scum and floating seeds are drawn off by an over- 

 flow pipe at the top of the tank, or skimmed off by a rake or 



