BLUING OF STEEL: See Steel.
BLUE PRINTS, TO MAKE CHANGES AND CORRECTIONS ON:
Use a solution of sodium carbonate and water, with a little red ink mixed in. This gives a very pleasing pink color to the changes which, at the same time, is very noticeable. The amount of sodium carbonate used depends upon the surface of the blue-print paper, as some coarse-grained papers will look better if less soda is used and vice versa. However, the amount of powdered soda held on a small coin dissolved in a bottle of water gives good results.
BLUE-PRINT PAPER MAKING: See Photography.
BLUE PRINTS, TO TURN BROWN: See Photography, under Toning.
BOIL REMEDY.
Take a piece of soft linen or borated gauze, rub some vaseline upon one side of it, quickly pour upon it some chloroform, apply it to the unopened boil or carbuncle, and place a bandage over all. It smarts a little at first, but this is soon succeeded by a pleasing, cool sensation. The patient is given a bottle of the remedy, and directed to change the cloth often. In from 2 hours to 1 day the boil (no matter how indurated) softens and opens.
BOILER COMPOUNDS
There are three chemicals which are known to attack boiler scale. These are caustic soda, soda ash, and tannic-acid compounds, the last being derived from sumac, catechu, and the exhausted bark liquor from tanneries.
Caustic soda in large excess is injurious to boiler fittings, gaskets, valves, {122} etc. That it is injurious, in reasonable excess, to the boiler tubes themselves is yet to be proved. Foaming and priming may be caused through excess of caustic soda or soda ash, as is well known by every practical engineer. Tannic acid is to be condemned and the use of its salts is not to be recommended. It may unite with the organic matter, present in the form of albuminoids, and with calcium and magnesium carbonates. That it removes scale is an assured fact; that it removes iron with the scale is also assured, as tannic acid corrodes an iron surface rapidly.