634 Foreign and Miscellaneous Intelligence. 



the various chemical apparatus they may require for their purpose. 

 I have frequently found the knowledge to be of importance, not only 

 as regards the time saved (and time is equal to money) ; but the 

 facility with which the various broken and otherwise useless articles 

 of domestic economy may be converted by its aid into convenient 

 and useful chemical apparatus. 



It will be unnecessary at present to enter into a detailed account 

 of the various apparatus that may be constructed, by any person ac- 

 quainted with the process it being my intention, on another occa- 

 sion, to describe a variety of such arrangements. My present object 

 is to describe the method by which the effect may be produced, with 

 certainty and despatch. 



The only tools requisite in this process are a few worn out three- 

 edged handsaw files ; these being generally made of cast steel, retain, 

 when ground, a very fine point, which is of the utmost importance. 

 In order, however, to give them the requisite degree of hardness, it 

 is necessary to make their ends, for about an inch, red hot, and then 

 plunge them into cold water ; by this treatment they become hard 

 and brittle : care is therefore required in grinding them to a proper 

 point ; this is easily effected on a common grindstone. I generally 

 give them a few rubs on a fine oil stone after the grinding, so as to 

 produce a very fine point. 



A cylindrical piece of any sort of wood, about two inches long, 

 terminated by a half round end, having a hole about the tenth of an 

 inch in diameter through its axis, may either be fastened into a com- 

 mon bench vice, or on a table ; this constitutes the only support 

 required. 



Suppose that a glass to cover the face of a wheel barometer is 

 wanted, through which it is sometimes necessary to make a perfora- 

 tion for the purpose of passing the screw of the nonius through: a 

 proper piece of glass being selected is to be marked with a dot of 

 ink on the place where the intended perforation is to be made ; the 

 glass is then to be held horizontally by the left hand, on and imme- 

 diately over the hole in the wood support above-mentioned. A 

 three edged file having been hardened, and ground to a fine point in 

 the manner before described, is held firmly between the forefinger and 

 thumb of the right hand, precisely in the position that a pen or pencil 

 is retained when writing. The pointed steel is then to be repeatedly 

 impinged against the glass over the spot intended to be perforated, 

 taking care not to use too much violence ; in a short time, the outer 

 surface is removed, and, by a continuation of the process, a conical 

 piece is forced from the under surface of the glass through the hole 

 in the wood support : the perforation so produced, never exceeds in 

 size a pin head, but may be made as large as required by holding it 

 over the hole in the support, and working round its edge with a fine 

 pointed file. In this way, after a little practice, and in a very few 

 minutes, may be perforated with ease all descriptions of glass, from 

 the thinnest crown to the thickest plate, without any danger. In- 



