44

ARTICLE XI.

SCALE OF HEAT

From the highest degree of heat produced in an air-furnace to the greatest degree of cold hitherto known, which was produced at Hudson's Bay, in December 1784, by a mixture of vitriolic acid and snow. See the American edition of the Encyclopedia, vol.xviii.p.500.

Fahrenheit Wedgwood's

	Fahrenheit	Wedgewoods's Scale
Extremity of Wedgwood's scale	322770	2400
Greatest heat of his small air-furnace	21877	160
Cast iron melts	17977	130
Greatest heat of a common smith's forge	17327	125
Welding heat of iron, greatest	13427	95
Welding heat of iron, least	12777	90
Fine gold melts	5237	32
Fine silver melts	4717	28
Swedish copper melts	4587	27
Brass melts	3807	21
Heat by which his enamel colours are burnt on	1857	6
Red heat fully visible in day-light	1077	1
Red heat fully visible in the dark	947	0
MERCURY BOILS, also linseed and other expressed oils	600
Oil of Turpentine boils	560
Sulphuric acid boils	546
Lead melts	540
Lead melts	460
Tin melts	408
Sulphur melts	244
Nitrous acid boils	242
Cows' milk boils	213
WATER BOILS	212
Human urine boils	206
Brandy boils	190
Alcohol boils	174
Serum of blood and white of eggs harden	156
Bees-wax melts	142
Heat of the air near Senegal sometimes	111
Hens hatch eggs about	108
Heat of birds from	103 to 111
Heat of domestic quadrupeds from	100 to103
Heat of the human body from	92 to 99
Heat of a swarm of bees	97
heat of the ocean under the equator	80
Butter melts	74
Vitriolic acid of the specific gravity of 1780 freezes at	45
Oil of olives begins to congeal	43
Heat of hedgehogs and marmots in a torpid state	39.5
WATER FREEZES and snow melts	32
Milk freezes	30
Urine and common vinegar freeze	28
Human blood freezes	25
Strong wines freeze	20
A mixture of one part of alcohol and three parts of water freezes	7
A mixture of snow and salt freezes	0 to 4
Brandy, or a mixture of equal parts of alcohol and water freezes	7
Spirits of wine in Reaumur's thermometer froze at Torneo	34
MERCURY FREEZES	39 tp 40
Cold produced by Mr.Macnab at Hudson's Bay, by a mixture of vitriolic acid and snow	69

46

A TABLE
Of the strength of Metals ascertained by experiments; the weight hung to an inch bar, with a straight pull. See the American edition of the Encyclopedia, vol. xvijj. p.10.

Metal		lbs.
Gold, cast		20,000
		24,000
Silver, cast		40,000
		43,000
Copper, cast	Japan	19,500
	Barbary	22,000
	Hungary	31,000
	Angelsea	34,000
	Sweden	37,000
Iron, cast		42,000
		59,000
Iron, bar	Ordinary	68,000
	Stirian	75,000
	Best Swedish & Russian	84,000
	Horse Nails	71,000
Steel, bar	Soft	120,000
	Razor temper	150,000
Tin, cast	Malaca	3,100
	Banca	3,600
	Block	3,800
	English block	5,200
	English grain	6,500
Lead, cast		860
Regulus of antimony		1,000
Zinc		2,600
Bismuth		2,900
Brass, a mixture of copper and zinc		51,000

47

"The expansion of bodies by heat is very various, and in solids does not seem to be guided by any certain rule. In the forty-eighth volume of the Philosophical Transactions, Mr. Smeaton has given a table of the expansions of many different substances, from which the following particulars are extracted. The degree of heat employed was 180 degrees of Fahrenheit's thermometer, and the expansion is expressed in 10,000th parts of an English inch."

Substance	10,000th parts of an English inch
A foot of white glass barometer tube	100
Martial regulus of antimony	130
Blistered steel	138
Hard steel	147
Iron	151
Bismuth	167
Hammered Copper	204
A mixture of 3 parts of copper with 1 of tin	218
Cast brass	225
A mixture of 16 parts of brass with 1 of tin	229
Brass wire	232
Speculum metal	232
Spelter solder, 2 parts brass and 1 zinc	247
Fine pewter	274
Grain Tin	298
Soft solder, 2 parts lead and 1 tin	301
A mixture of 8 parts of zinc and one of tin, a little hammered	323
Lead	344
Zinc or spelter	353
Zinc hammered an inch per foot	373

| YOUNG STEAM ENGINEER'S GUIDE |ARTICLE XII |