ACID PROOFING FOR DESKS 



II 



plug of the large tube and sterilize. During sterilization the fluid enters the mouth 

 of the smaller tube and fills it, and when the medium is subsequently inoculated, if 

 gas forms, it appears in the upper part of the closed end of the smaller tube. 



For inspissating blood-serum slants a regular inspissator is desirable. 

 This is nothing more than a double-walled vessel, the space between 

 the walls being filled with water. 



As a substitute one may take the common rice cooker (double boiler). Fill the 

 outer part with water; and in the inner compartment pack the serum tubes properly 

 slanted on a piece of wood or a wedge-shaped layer of cotton. Place a weight on 

 the cover of the inner compartment to sink it 

 into the surrounding water, and allow to boil 

 for one or two hours. This same apparatus 

 may be used for their sterilization on two sub- 

 sequent days, but it is better to sterilize in the 

 autoclave or Arnold. As regards a working 

 desk, it will be found convenient to have an 

 arrangement similar to the ordinary flat-top 

 desk, with a tier of drawers on each side. A 

 block of wood with holes bored in it to contain 

 dropping-bottles may be placed in the upper 

 lef thand drawer. In this way the stains are as 

 accessible as if they encumbered the desk. It is advisable to paint the inside of this 

 drawer black so that the light may not cause the staining reagents to deteriorate. 



A very popular method of preparing the surfaces of laboratory 

 desks, sinks, and tables is the application of the so-called " acid-proofing." 

 This gives an ebony-like finish- which is not affected by strong acids. 



In using it the surface of the wood must be new (free of any varnish, oil, or 

 paint; if previously so coated the surface must be planed). 



FIG. 5. Rice cooker. 



Solution i. 



Potassium chlorate, 

 Cupric sulphate, 

 Water, 



125.0 gms. 

 125.0 gms. 

 i ooo.o c.c. 



Apply two coats of this solution at least 1 2 hours between applications. When 

 thoroughly dry apply two coats of solution No. 2. 



Solution 2. 



Aniline oil, 

 Hydrochloric acid, 

 Water, 



I2O.O C.C. 



180.0 c.c. 



IOOO.O C.C. 



When the treated surface is thoroughly dry apply one coat of raw linseed oil 

 with a cloth. After this is dry wash with very hot soapsuds. 



