426 MOLESWORTH’S POCKET-BOOK
Workshop Beoipes—continued.
Case-hardening.
Place horn, hoof, bone-dust, or shreds of leather,
together with the article to be case-hardened, in
arT iron box subject to a blood-red heat, then
immerse the article in cold water.
Some engineers cut up the shreds, &c., fine,
and mix them with white wino vinegar, and salt.
CASE-HARDENING WITH PRUSSIATE OF POTASH.
Heat the articles after polishing to a bright red,
rub the surface over with prussiate of potash;
allow it to cool to dull red, and immerse it in
water.
CASE-HABT>ENING MIXTURES.
3 prussiate of potash to 1 of sal-ammoniac
mixed, or 2 sal-ammoniac, 2 of bone-dust, and 1
of prussiate of potash.
Glue to Resist Moisture. _
1 lb. of glue melted in 2 quarts of skimmed
When strong glue is required add powdered
chalk to common glue.
Marine Glue.
1 of india-rubber, 12 of mineral naphtha or
coal-tar, h,eai gently, mix, and add 20 of powdered
shellac. Pour out on a slab to cool—when used
to be heated to about 250°. ’
Glue Cement to Resist Moisture.
J ?!ue. • I mixed with the least possible
1 black rosin > quantity of water.
2 red ochre J 1 J
A DI OR.
4 of glue,
1 of boiled oil by weight.
1 oxide of iron.