N I T

NIT

( HS )

abforb the acid which the water would not con-denfe, and thus by fubfequent calculationsfounded on the fpecific gravity of the gaffesufed and the acid product, to find a ftandard acid ,the compofition of which fhould be accuratelyknown. It will not be uninterelting to givein a general way the particulars of the ftandardexperiment, to fihew more clearly the mannerof effecting it, and alfo the numerous data andcalculations required to come at the refult.

The firft ftep was to afcertain by actual ex-periment the fpecific gravity of all the gaffesto be employed. The nitrous gas was procuredfrom a folution of mercury in nitrous acid, andits purity tried by agitating a fmall portion witha folution of fulphat of iron, by which the wholeof the nitrous gas was abforbed, and nearly allthe azot mixed with it was left: xoo cubicinches of pure nitrous gas were found to weigh34.3 grains at 56° therm, and 30.9 bar. Theoxygen gas was obtained from oxyd of manga-nele by fulphuric acid, and its purity tried bynitrous gas and fulphat of iron. Hence 100cubic inches of pure oxygen gas at the aboveheat and pmffure, were found to weigh 35.09grains. The azotic gas was obtained from therefidue of common air after the oxygen hadbeen abforbed, and 100 cubic inches weighed30.43 grains. Laftly the atmofpherical air ofthe laboratory was analyfed, and 100 cubicinches of it weighed 31.9 grains. The experi-ment was then conducted in the followingmanner.

A glafs balloon with a (top-cock, of the capa-city of 148 cubic inches, was taken for thepurpofe of combining the gaffes. The wholeweight when full of common air was 2066.5grs. It was then partially exhaufted by the airpump, till it loft 32 grains, fo that 15 grains ofair remained in it. After this 82 cubic inchesof nitrous gas were thrown in, which made theoutfide of the balloon fenfibly hot, and producedan orange coloured vapour within. Some com-mon air then entered accidentally, the weightof which was noted. Then 70 cubic inches ofoxygen gas were introduced, whereby the heatwas increafed and the colour changed to a verydark orange. To abforb the nitrous acidformed, \ 1 grains of water were introduced,by which the dark orange colour rapidly dimi-nifhed and foon disappeared. To afcertain thequantity of vapour co .denfed by the water,the vacuum produced thereby was filled withcommon air, of which 31 cubic inches, or 16.5•grains, rallied in. The acid liquor in the globe(produced by the water and the acid vapour,

which it had condenfed) was then' examined,and was found (lightly green, and of 1.301fpecific gravity.

To find whether any unabforbed nitric acidremained in the veffel, 13 grains of liquid am-monia were added, which produced a whitecloud with the remaining acid vapour, afterwhich all the refidual gaffes were difplaced bycommon air. The balloon was weighed afterevery procefs. By calculations from the aboveexperiment it was found that 57 cubic inches ofacid gas were formed, weighing 40.56 grains;this was compofed of 27.6 grains, or 80.5cubic inches of azot, and 12.96 grains, or36.9 cubic inches of oxygen, which, condenfedby 41 grains of water, produced an acid of1.301 fpecific gravity. Therefore, reducingthe whole to centenary proportion, 100 cubicinches of aeriform nitrous acid (or nitrous gasfaturated with oxygen and excluded from thecontadl of water or any other fubftance thatcould a£i upon or abforb it) at temperature■ 55 0 and 30.1 bar. weigh 75.17 grains.

Secondly: 100 grs. of this gaffeous acid arecompofed of 68.06 nitrous gas and 31.94 oxy-gen ; or (affuming that 100 parts of nitrous gasconfilt of 55.95 oxygen and 44.05 azot, as willbe mentioned under the article nitrous gas ) ofabout 30 azot and 70 oxygen.

Thirdly, 100 grs. of a pale green folutionof this acid in water, of 1.301 fp. gr. arecompofed of 50.62 water and 49.38 acid.

A ftandard acid of known compofition wasthus obtained, but it was dilute, and many ofthe fubfequent experiments were to be per-formed on the concentrated acid. But as thereis no known method of concentrating a diluteacid without partial decompofition, Mr. D. wasobliged to make a dilute acid compofed of agiven quantity of the ftrongeft yellow acid of1.5 fp. gr. and water, which fhould as nearlyas poffible refemble in weight and colour theftandard acid produced by the union of thegaffes. This after many trials in a fmall gra-duated glafs tube was found to be eflefted bycombining at 40° therm. 90 grs. of the yellowacid of 1.5. fp. gr. with 77.5 grs. of water,and hence the compofition of the above yellowacid was inferred to be, in 100 grs. 91.9 of truenitrous acid ("or fuch as exiiis in the aeriformftate faturated with oxygen) and 8.x grs. ofwater, fuppofing the relative quantities of oxy-gen and azot to be the fame in each.

But on the other hand the acid of 1.5 hereufed was the yelicnu or nitrous acid, and'it be-came a further queftion to afcertain the precife