226 
ELEMENTS OF SOILS. 
Sulphur. This well known substance is widely disseminated in the mineral kingdom, 
and is also found sparingly in the vegetable and animal kingdoms. The two most common 
combinations are sulphurets and sulphates. In the former condition it is combined with 
the metals ; in the latter, with oxygen, forming sulphuric acid. In this state it combines 
with earths and alkalies, and forms salts, as sulphate of lime, of soda, of magnesia, etc. 
It is an important substance. It is obtained mostly from Sicily, and is a volcanic product, 
resulting from the sublimation of a native sulphuret. It may be also procured in this State, 
by the roasting of certain ores in which it abounds. 
Phosphorus. In its pure state, this is a white solid, highly inflammable, comparatively 
soft and flexible at blood heat, and taking fire readily by friction. It is quite abundant in 
the animal kingdom, in combination with oxygen, forming phosphoric acid, which, like 
the sulphuric acid, combines with lime and other bases, forming salts. The phosphate of 
lime is its most common combination. It is an essential constituent of bones, and of the 
coverings of many marine animals, forming in both cases the hard substantial part of the 
animal. It is also met with in the mineral kingdom. It is contained in all good soils, 
but only in small quantities when compared with the other elements. It exists in combi¬ 
nation with lime, iron and alumina, and is detected with difficulty. Both phosphorus and 
sulphur form constituent parts of proteine , which is regarded as the basis of albumen, fibrine 
and caseine. 
Carbonic acid. It is a constant constituent of the atmosphere. Its origin is not known : 
it is, however, a constant product of combustion and respiration, and in this way continu¬ 
ally escapes into the atmosphere. It also escapes from the earth in the neighborhood of 
volcanoes; but it is here one of the results of combustion, or of the action of heat on the 
limestone contained in the interior of the earth. It is heavier than atmospheric air, and, 
hence, if operated on by its specific gravity only, would always be found on the surface of 
the earth; but gases, when mixed, never behave like liquids, where the heaviest finds 
the bottom and the lightest the top : they, on the contrary, become equally mixed, and all 
parts of a volume will be found to contain the same proportion of the heavier and the 
lighter gas. 
Carbonic acid is a poison. When inhaled, death speedily follows, unless means are soon 
instituted for counteracting its effects. It is not simply a deprivation of oxygen. It extin¬ 
guishes a burning taper if immersed in it, or even if it be simply poured over the taper. 
Hence by trying a suspected gas with a lighted taper, it may be known whether carbonic 
acid is present. When mixed with air in the proportion of 1 to 10, it still remains irrespi- 
rable, producing stupor and death like a narcotic poison. Its specific gravity is 1.52. It 
dissolves in water, forming an agreeable acid taste. It turns litmus paper red. 
Carbonic acid is liquid under a pressure of 36 atmospheres = 15 lbs. x 36 on the square 
inch. If the pressure is suddenly removed, the evaporation is so rapid that a portion of 
the liquid solidifies from the loss of heat. 
Carbonic acid has a wide range of affinity. It is one of the important and most common 
of the compound elements. This importance is due partly to the ease with which it may 
