Elements of Chemistry Part 34

6. Gold, silver, and probably platina, are slowly volatilized without any particular phenomenon.

7. All other metallic substances, except mercury, become oxydated, though placed upon charcoal, and burn with different coloured flames, and at last dissipate altogether.

8. The metallic oxyds likewise all burn with flames. This seems to form a distinctive character for these substances, and even leads me to believe, as was suspected by Bergman, that barytes is a metallic oxyd, though we have not hitherto been able to obtain the metal in its pure or reguline state.

9. Some of the precious stones, as rubies, are capable of being softened and soldered together, without injuring their colour, or even diminishing their weights. The hyacinth, tho' almost equally fixed with the ruby, loses its colour very readily. The Saxon and Brasilian topaz, and the Brasilian ruby, lose their colour very quickly, and lose about a fifth of their weight, leaving a white earth, resembling white quartz, or unglazed china. The emerald, chrysolite, and garnet, are almost instantly melted into an opake and coloured gla.s.s.

10. The diamond presents a property peculiar to itself; it burns in the same manner with combustible bodies, and is entirely dissipated.

There is yet another manner of employing oxygen gas for considerably increasing the force of fire, by using it to blow a furnace. Mr Achard first conceived this idea; but the process he employed, by which he thought to dephlogisticate, as it is called, atmospheric air, or to deprive it of azotic gas, is absolutely unsatisfactory. I propose to construct a very simple furnace, for this purpose, of very refractory earth, similar to the one represented Pl. XIII. Fig. 4. but smaller in all its dimensions. It is to have two openings, as at E, through one of which the nozle of a pair of bellows is to pa.s.s, by which the heat is to be raised as high as possible with common air; after which, the stream of common air from the bellows being suddenly stopt, oxygen gas is to be admitted by a tube, at the other opening, communicating with a gazometer having the pressure of four or five inches of water. I can in this manner unite the oxygen gas from several gazometers, so as to make eight or nine cubical feet of gas pa.s.s through the furnace; and in this way I expect to produce a heat greatly more intense than any hitherto known.

The upper orifice of the furnace must be carefully made of considerable dimensions, that the caloric produced may have free issue, lest the too sudden expansion of that highly elastic fluid should produce a dangerous explosion.

FINIS.

APPENDIX.

No. I.

TABLE _for Converting Lines, or Twelfth Parts of an Inch, and Fractions of Lines, into Decimal Fractions of the Inch._

Twelfth Parts Decimal Decimal of a Line. Fractions. Lines. Fractions.

1 0.00694 1 0.08333 2 0.01389 2 0.16667 3 0.02083 3 0.25000 4 0.02778 4 0.33333 5 0.03472 5 0.41667 6 0.04167 6 0.50000 7 0.04861 7 0.58333 8 0.05556 8 0.66667 9 0.06250 9 0.75000 10 0.06944 10 0.83333 11 0.07639 11 0.91667 12 0.08333 12 1.00000

No. II.

TABLE _for Converting the Observed Heighths of Water in the Jars of the Pneumato-Chemical Apparatus, expressed in Inches and Decimals, into Corresponding Heighths of Mercury._

Water. Mercury. Water. Mercury.

.1 .00737 4. .29480 .2 .01474 5. .36851 .3 .02201 6. .44221 .4 .02948 7. .51591 .5 .03685 8. .58961 .6 .04422 9. .66332 .7 .05159 10. .73702 .8 .05896 11. .81072 .9 .06633 12. .88442 1. .07370 13. .96812 2. .14740 14. 1.04182 3. .22010 15. 1.11525

No. III.

TABLE _for Converting the Ounce Measures used by Dr Priestly into French and English Cubical Inches._

Ounce French cubical English cubical measures. inches. inches.

1 1.567 1.898 2 3.134 3.796 3 4.701 5.694 4 6.268 7.592 5 7.835 9.490 6 9.402 11.388 7 10.969 13.286 8 12.536 15.184 9 14.103 17.082 10 15.670 18.980 20 31.340 37.960 30 47.010 56.940 40 62.680 75.920 50 78.350 94.900 60 94.020 113.880 70 109.690 132.860 80 125.360 151.840 90 141.030 170.820 100 156.700 189.800 1000 1567.000 1898.000

No. IV. ADDITIONAL.

TABLE _for Reducing the Degrees of Reaumeur's Thermometer into its corresponding Degrees of Fahrenheit's Scale._

R. F. R. F. R. F. R. F.

0 = 32 21 = 79.25 41 = 124.25 61 = 169.25 1 = 34.25 22 = 81.5 42 = 126.5 62 = 171.5 2 = 36.5 23 = 83.75 43 = 128.75 63 = 173.75 3 = 38.75 24 = 86 44 = 131 64 = 176.

4 = 41 25 = 88.25 45 = 133.25 65 = 178.25 5 = 43.25 26 = 90.5 46 = 135.5 66 = 180.5 6 = 45.5 27 = 92.75 47 = 137.75 67 = 182.75 7 = 47.75 28 = 95 48 = 140 68 = 185 8 = 50 29 = 97.25 49 = 142.25 69 = 187.25 9 = 52.25 30 = 99.5 50 = 144.5 70 = 189.5 10 = 54.5 31 = 101.75 51 = 146.75 71 = 191.75 11 = 56.75 32 = 104 52 = 149 72 = 194.

12 = 59 33 = 106.25 53 = 151.25 73 = 196.25 13 = 61.25 34 = 108.5 54 = 153.5 74 = 198.5 14 = 63.5 35 = 110.75 55 = 155.75 75 = 200.75 15 = 65.75 36 = 113 56 = 158 76 = 203 16 = 68 37 = 115.25 57 = 160.25 77 = 205.25 17 = 70.25 38 = 117.5 58 = 162.5 78 = 207.5 18 = 72.5 39 = 119.75 59 = 164.75 79 = 209.75 19 = 74.75 40 = 122 60 = 167 80 = 212 20 = 77

_Note_--Any degree, either higher or lower, than what is contained in the above Table, may be at any time converted, by remembering that one degree of Reaumeur's scale is equal to 2.25 of Fahrenheit; or it may be done without the Table by the following formula, R 9 / 4 + 32 = F; that is, multiply the degree of Reaumeur by 9, divide the product by 4, to the quotient add 32, and the sum is the degree of Fahrenheit.--E.

No. V. ADDITIONAL.

RULES _for converting French Weights and Measures into correspondent English Denominations[62]._

-- 1. _Weights._

The Paris pound, poids de mark of Charlemagne, contains 9216 Paris grains; it is divided into 16 ounces, each ounce into 8 gros, and each gros into 72 grains. It is equal to 7561 English Troy grains.

The English Troy pound of 12 ounces contains 5760 English Troy grains, and is equal to 7021 Paris grains.

The English averdupois pound of 16 ounces contains 7000 English Troy grains, and is equal to 8538 Paris grains.

To reduce Paris grs. to English Troy } grs. divide by } 1.2189 To reduce English Troy grs. to Paris } grs. multiply by }

To reduce Paris ounces to English } Troy, divide by } To reduce English Troy ounces to } 1.015734 Paris, multiply by }

Or the conversion may be made by means of the following Tables.

I. _To reduce French to English Troy Weight._

The Paris pound = 7561 } The ounce = 472.5625 } English.

The gros = 59.0703 } Troy.

The grain = .8194 } Grains.

II. _To Reduce English Troy to Paris Weight._

The English Troy pound } = 7021. } of 12 ounces } } The Troy ounce = 585.0830 } The dram of 60 grs. = 73.1353 } Paris The penny weight, or } = 29.2540 } grains.

denier, of 24 grs. } } The scruple, of 20 grs. = 24.3784 }

III. _To Reduce English Averdupois to Paris Weight._

The averdupois pound of } } 16 ounces, or 7000 } = 8538. } Paris Troy grains. } } grains.

The ounce = 533.6250 }

-- 2. _Long and Cubical Measures._