CHEMISTRY. 



In proper- 

 lie*. 



TVblfofihe 

 strength 

 and boiling 

 po nc of 

 ulphuric 

 ac.d. 



tcr. The icid formed it dissolved by the water, and 

 it concentrated by distillation in glats retorti. 



Sulphuric acid ii liquid, somewhat of an oily con- 

 listener, transparent and colourless as water, without 

 any smcH, and of a very strong acid taste. It de- 

 stroys the texture of animal and vegetable substances. 

 Its specific gravity, when as strong as possible, is 

 about 1 85. It changes all vegetable blues to red, 

 except indigo. When of the specific gravity 1.8*4, 

 it boils at .5^6. When exposed to cold, it crystalli- 

 zes or congeals. The temperature necessary depends 

 upon tbe strength. When of the specific gravity 

 1.7W. it freezes at 4-5. When stronger or weaker, 

 it requires a much greater degree of cold. 



It has a strong attraction for water, and when ex- 

 posed to the atmosphere, imbibes nearly seven times 

 its weight of that liquid. When the two liquids are 

 mixed together, a considerable heat is evolved. Thus 

 four parts of acid and one of water raises the ther- 

 mometer to about 300. The density of this mix- 

 ture is always considerably greater than the mean. 

 From the experiments of Kirwan, it appears that the 

 strongest sulphuric acid of commerce contains almost 

 1 -5th of water, the remaining 4-5ths are pure acid. 



The following Table, drawn up by Mr Dalton 

 from his own experiments, exhibits the strength and 

 the boiling point of sulphuric acid of various densi- 

 ties. 



Compoti- From the most accurate experiments hitherto made, 

 sulphuric acid appears to be composed of 

 60 oxygen. 

 40 sulphur. 



100 



This acid is not altered by exposure to light nor 

 heat. Oxygen gas does not act upon it nor combine 

 with it. 



The simple combustibles have but little effect up. 

 on it at the ordinary temperature of the atmosphere, 

 but when assisted by heat, they all decompose it. 

 When hydrogen gas and the acid are passed through 

 a red-hot tube, water is formed, and sulphur deposit- 

 ed. Charcoal absorbs oxygen from it, and readily 

 convent it into sulphurous acid, or into sulphur, if 



the heat be long continued. Phosphorui and bora- Elontnn 

 cium produce the same effect. Sulphur, when boiled of . 

 with it, readily converts it into sulphurous acid. 



Azote has no action on it ; but it readily absorbs 

 muriatic acid, and forms a smoking compound, which 

 acts powerfully upon some metals. 



Sulphuric acid, when concentrated, has little action 

 on the metals. When diluted, it di->olves iron and 

 zinc with rapidity, water is decomposed, and hydro- 

 gen gas emitted. When heated, it oxidizes several 

 of the metals, and sulphurous acid is exhaled. On 

 gold and platinum it produces no effect whatever. 



It unites readily with the alkalies, earths, and me- 

 tallic oxides ; and forms with them a class of bodies 

 called sulphates. 



It absorbs a good deal of nitrous gas, and acquires, 

 in consequence, a purplich colour. 



This acid is of great importance, both in chemistry 

 and the art*. 



SBCT. II. Of Sulphurous Acid. 



The existence of this acid was pointed out by Stalil, Sulphurous. 

 but Priestley was the first who procured it in a sepa- at ' d - 

 rate state. It may be obtained by distilling in a re- How ob- 

 tort a mixture of two parts sulphuric acid, and one "uued. 

 part of mercury. An effervescence takes place, and 

 a gas comes over, which may be received in jars over 

 mercury. 



It is colourless, and possesses the mechanical pro- Its proper, 

 perties of common air. It has a strong and suffoca- ''* 

 ting odour, precisely the same as that emitted by 

 burning sulphur. Its specific gravity is 2.265, that 

 of air being 1.000. It reddens vegetable blues, and 

 gradually destroys the colour altogether. 



When strongly heated, sulphur is deposited, and 

 sulphuric acid formed. When exposed to the tem- 

 perature of 18, it is condensed into a liquid. 



Water absorbs 33 times its bulk of this gas. The 

 liquid has the smell of the gas, an acid and sulphure- 

 ous taste, and the specific gravity 1.0513. It may 

 be frozen without parting with the gas. But when 

 heated, the gas is expelled. When this liquid is left 

 to itself, it gradually absorbs oxygen, and the acid ia 

 converted into the sulphuric. 



Sulphur and phosphorus seem to have no action 

 on this acid ; but hydrogen and charcoal decompose 

 it when assisted by heat, and sulphur is evolved. 

 Neither azote nor muriatic acid produce any effect 

 upon it. 



It oxidizes and dissolves iron, zinc, and manganese. 



It combines with the salifiable bases, and forms 

 salts called sulphites. 



Sulphuric acid absorbs it, and forms a singular 

 compound called gletfial sulphuric acid, which readily 

 becomes solid, and smokes when exposed to the air. 



Its constituents are 50 sulphur, Composi- 



50 oxygen. I0n * 



100 



SECT. I II. Of Phosphoric Acid. 



This acid was first mentioned by Boyle, but its Phosphoric 

 properties were investigated many years after. It may * cld4 



