At this stage of the process the liquor becomes so loaded with carbon, and at the same time is capable of bearing so high a temperature, that if the heat is kept up, the sulphuric acid is decom posed, and a large quantity of sulphu rous acid gas and carbonic acid is pro duced. If the greatest care is not taken to keep the heat moderate, the whole. liquor is apt to swell suddenly up, and boil over into the receiver. If examined at this time, it is likewise found to con tain a portion of acetic and oxalic acids mixed with the sulphuric acid, which is diluted with water, and through which the carbon is diffused. Sulphuric ether, when highly rectified, is the lightest of all known liquids. It is obtained without difficulty of the specific gravity of .732, and by careful distillation has been brought so low as .716. It is colourless, and perfectly transparent ; has a strong pungent taste, and a fragrant penetrating smell.
It is likewise the most volatile liquid. It evaporates rapidly, even at the com mon temperature, and under the com mon pressure of the atmosphere ; so that it cannot be poured from one vessel into another without loss, and any part wet with it immediately becomes dry. In vacuo it boils at a temperature consi derably below 32° : under the atmosphe ric pressure it boils at 98. In the spon taneous evaporation of ether a large quantity of caloric is absorbed, so as to produce cold: water inclosed in a small tube may be easily frozen, by ether eva porating from a piece of muslin wrapt round the external surface of the tube ; and Dr. Higgins has observed, that in the rapid evaporation of ether, the tempera ture in frosty weather falls so low as 40. Ether congeals at 47.
Ether is highly inflammable, and, when kindled, burns with a clear white flame, without any smoke, and without leaving any residuum, the products of its com bustion being water and carbonic acid : the residual water generally gives indica tions too of sulphuric acid, which may either be adventitious, or perhaps is es sential to the constitution of this species of ether. From its high inflammability, its vapour diffused in the atmosphere sometimes takes fire ; or if a drop or two of ether be added to atmospheric air, or oxygen gas, an explosion happens on the contact of an ignited body.
Sulphuric ether is soluble in water; but only in a limited proportion. When highly rectified, it requires ten parts of waterfor its solution ; and this is a proper ty by which we are enabled to determine its purity, as, if more soluble, it contains either water or alcohol. It is soluble in alcohol in every proportion.
Sulphuric ether exerts no sensible ac tion on the fixed alkalies or earths. It
unites with ammonia by distillation.
Neither does it act on the metals ; but it of d ns of the weak to oxygen, by attracting thlt Thus, muriate of gold dis solved in it is gradually decomposed, and the gold precipitated in its metallic (form.
On the simple inflammables its action is somewhat similar to that of alcohol. It dissolves sulphur, as Favre has shown, • one ounce of ether dissolving about 25 ' grains; the solution has a strong sul phurous smell and taste ; it is less soluble in water than pure ether, and deposits sulphur as the ether volatilizes. ("Ni cholson's Journal," vol. xiii. p. 69.) Eth er likewise dissolves a small proportion of nhosnhorus ; this solution, like the phosphuretted alcohol, is decomposedby water ; but does not, like it, appear lumi nous during the decomposition.
Sulphuric ether is a solvent of many of the vegetable proximate principles,_ as the essential oils, camphor, and resins. It is also, as has already been remarked. the most powerful solvent of caoutchouc.
In medicine it is employed as a diffusi ble stimulant.
Nitric Ether. The action of nitric acid on alcohol is so violent, that the formation of nitric ether is extremely difficult, and requires considerable precaution. One part of the acid may be added gradually to three parts of alcohol without any risk ; and after standing for some days, to allow of their reciprocal action, heat may be applied, when a portion of nitric ether that has been formed distils over, with a quantity of unchanged alcohol. A preparation of this kind has been long known in pharmacy, under the name of sweet spirit of nitre. But when the pro portion of acid is increased, the action becomes very violent ; a quantity of aerial fluid is suddenly formed, and disengaged at each addition; and it requires parti cular arrangements, to admit of so much acid being added, as is sufficient tQ convert the whole of the alcohol into ether.
The method proposed by Navier is, to put into a strong earthenware bottle twelve parts of alcohol, and immerse it in water or ice ; eight parts of nitrous acid are to be added in successive portions, mixing them by agitation at each addi tion ; the bottle is well corked, and tied over, and is put in a cool place. At the end of six days the cork is to be perfo rated, to allow a quantity of gaseous fluid that has been formed, and is retained by compression, to escape. The bottle is then uncorked, the liquid poured into a funnel, and the acid liquor beneath allow ed to run off from the ether which swims above.