Acid Proofing

Acid-Proofing

An Acid-Proof Table Top.‑

1. 

Copper sulphate ............  1 part

Potassium chlorate.. .....  1 part

Water... ...... .  .......... 8 parts

Boil until salts are dissolved.

2. 

Aniline hydrochlorate. 3 parts Water            20 parts
Or, if more readily procurable:

Aniline .............................. 6 parts

Hydrochloric acid........... 9 parts

Water    50 parts

By the use of a brush two coats of so­lution No. 1 are applied while hot; the sec­ond coat as soon as the first is dry. Then two coats of solution No. 2, and the wood allowed to dry thoroughly. Later, a coat of raw linseed oil is to be applied, using a cloth instead of a brush, in order to get a thinner coat of the oil.

A. writer in the Journal of Applied Microscopy states that he has used this method upon some old laboratory tables which had been finished in the usual way, the wood having been filled oiled, and varnished. After scraping off the varnish down to the wood, the solutions were ap­plied, and the result was very satisfac­tory.

After some experimentations the for­mula was modified without materially affecting the cost, and apparently in­creasing the resistance of the wood to the action of strong acids and alkalies. The modified formula follows:

1.

Iron sulphate   4 parts Copper sulphate  4 parts Potassium permanga‑

nate .............................. 8 parts

Water, q. s................ .100 parts 2.

Aniline ............................ 12 parts

Hydrochloric acid ..          18 parts

Water, q. s............... .100 parts
Or:

Aniline hydrochlorate 15 parts
Water, q. s....               ...100 parts

Solution No. 2 has not been changed, except to arrange the parts per hundred.

The method of application is the same, except that after solution No. 1 has dried, the excess of the solution which has dried upon the surface of the wood is thor­oughly rubbed off before the application of solution No. 2. The black color does not appear at once, but usually requires a few hours before becoming ebony black. The linseed oil may be diluted with turpentine without disadvantage, and after a few applications the surface will take on a dull and not displeas­ing polish. The table tops are easily cleaned by washing with water or suds after a course of work is completed, and the application of another coat of oil puts them ifi excellent order for another course of work. Strong acids or alkalies when spilled, if soon wiped off, have scarcely a perceptible effect.

A slate or tile top is expensive not only in its original cost, but also as a destroyer of glassware. Wood tops when painted, oiled, or paraffined have objectionable features, the latter especially in warm weather. Old table tops, after the paint or oil is scraped off down to the wood, take the above finish nearly as well as the new wood.

To Make Wood Acid- and Chlorine­Proof.—Take 6 pounds of wood tar and 12 pounds rosin, and melt them together in an iron kettle, after which stir in 8 pounds finely powdered brick dust. The damaged parts must be cleaned perfectly and dried, whereupon they may be painted over with the warm preparation or filled tip and drawn off, leaving the film on the inside.

Protecting Cement Against Acid.—A paint to protect cement against acid is obtained by mixing pure asbestos, very finely powdered, with a thick solution of

sodium silicate. The sodium silicate must be as alkaline as possible. The asbestos is first rubbed with a small quantity of the silicate, until a cake is obtained and then kept in well-closed vessels. For use this cake is simply thinned with a solution of the silicate, which furnishes a paint two or three ap­plications of which protect the walls of reservoirs, etc., against any acid solid or liquid. This mass may also be em­ployed for making a coating of sand­stone.

To Make Corks Impermeable and Acid-Proof.--Choose your corks care­fully. Then plunge them into a solution of gelatin or common glue, 15 parts, in 24 parts of glycerine and 500 parts of water, heated to 44° or 48° C. (112°-1e0a F.), and keep them there for several hours. On removing the corks which should be weighted down in the solution, dry them in the shade until they are free from all surplus moisture. They are now perfectly tight, retaining at the same time the greater portion of their elasticity and suppleness. To render them acid-proof, they should be treated with a mixture of vaseline, 2 parts, and paraffine 7 parts, heated to about 105° F. This second operation may be avoided by adding to the gelatin solution a little ammonium dichromate and afterwards exposing the corks to the light. 

Lining for Acid Receptacles.—Plates

are formed of 1 part of brown slate, 2 of powdered glass, and 1 of Portland cement, the whole worked up with sili­cate of soda, molded and dried. Make a cement composed of ground slate and silicate of soda and smear the surface for the lining; then, while it is still plastic, apply the plates prepared as above de­scribed. Instead of these plates, slabs of glass or porcelain or similar substances may be employed with the same cement.