western settlement, Illinois was three or four weeks from New York, it is now but three days. Minnesota, which could then scarcely have been reached in six weeks, is now but four days from the Atlantic seaboard.

These are permanent causes. Foreign emigration might be directed to entirely new fields, without greatly diminishing their effect. Looking to the operation of these causes alone, what will be the future growth of Minnesota Taking as a basis of calculation the neighboring States of Iowa and Wisconsin, the position and characteristics of which are both combined in Minnesota, we have compared their growth with that of Minnesota for the decade corresponding, as to the numerical starting points, with that of Minnesota between 1850 and 1860. We have already shown that Minnesota, in the first decade of her growth, increased in population 3217 per cent, against an average of 892 per cent for the corresponding period of the growth of Wisconsin and Iowa. Starting in 1832 with the population of Minnesota in 1850, Wisconsin was fifteen years and Iowa seventeen in acquiring the population (172,000) which Minnesota gained in ten. Their growth after that period was as follows:

Wisconsin...
Iowa....

1847-180,000
1850-192,000

Ratio of increase.

1857-650,000 261
1860-675,000

251

So that moving upon the same plane of progression as Iowa and Wisconsin, Minnesota, starting upon her second decade with a population of 172,000, should have in 1870 a population of 610,000, or 261 per cent increase; and in 1880, moving only at the speed of Illinois, she would have 1,300,000, or a little over 100 per cent increase. This increase, at least, is assured to us by the pressure of causes permanent in their character, and unceasing in their operation. But much more than this is assured to us by the law of a constantly increasing rapidity of frontier growth which our citations have demonstrated.

In our first decade, in accordance with this law, our population increased more than three times as fast as that of Wisconsin and Iowa for the corresponding period of their growth, dating from the same point in population. If we should allow for the next decade an addition of only 50 per cent over their ratios of growth, it would give us in 1870 a population of 845,000; and if we add 50 per cent only to the ratio of Illinois for the next decade, we shall have a population in 1880 of over 2,112,000 -results which we may calculate upon with reasonable certainty.

But to the agencies already noticed, as accelerating the increase of population in the new States, must be added another element in the future growth of Minnesota, which must come into full and effective operation before the close of the present decade, and that is the restricted supply of fertile lands for the formation of new settlements in the West and South, and the consequent inevitable determination of the whole westward movement of population in the direction of Minnesota and the northwestern valleys of whose outlets she holds the keys. Thus imperative physical conditions co-operate with the established laws and tendencies of frontier growth to promise an augmentation of population in Minnesota in the next twenty years, far greater than has been attained in an equal period by any State of the Union.

DISTILLATION OF PETROLEUM.

SPECIFICATIONS OF THE PATENT GRANTED TO CHARLES BLACHFORD MANSFIELD, OF CLARE HALL, IN THE UNIVERSITY OF CAMBRIDGE, FOR AN IMPROVEMENT IN THE MANUFACTURE AND PURIFICATION OF SPIRITUOUS SUBSTANCES, AND OILS APPLICABLE TO THE PURPOSES OF ARTIFCIAL LIGHT AND VARIOUS USEFUL ARTS.*

THE first part of my invention relates to the manufacture of certain spirituous substances and oils, and consists in treating tars and bituminous substances, or the oils obtained from them, so that the most volatile, oily, or spirituous substances which are contained in them are separated, viz., such as are so volatile that a current of air passed through them at ordinary atmospheric temperatures, will take up so much of their vapor as to burn with a white flame; and this part of the invention also relates to separating from each other certain oils and spirituous substances, which are contained in the tar or oily matter, distilled from any of the different varieties of mineral coal, when coal is distilled either alone or mixed with other substances, either in the process for making illuminating gas, or in any processes in which coal is submitted to destructive distillation, which oils and spirituous substances have not hitherto been obtained separate from coal-tar and from each other. This part of the invention also relates to the conversion of some of the oils and spirituous substances separated from coal-tar into fragrant oil by the action of nitric acid.

Since that part of my invention which is applicable to bituminous oils and tars generally is applicable particularly to coal-tar, I will first describe its application to coal-tar, and will then show its general application to other tars and bituminous oils.

In order that my invention may be most fully understood, I will first state briefly the nature of the substances usually prepared from coal-tar by distillation, and then I will explain what are the peculiar properties of the substances which I obtain, and then I will describe the means pursued by me in order to obtain substances possessing such properties.

It must be understood that coal tar is not a substance of invariably similar constitution, but that though its constituents are generally the same, their proportions vary in different samples, and the causes of the variations therein are not yet understood.

In the distillation of coal-tar the products which are generally recog nized as distinct, and are separated from each other, are ammoniacal water, oil heavier than water, which is usually called dead oil, and oil lighter than water. The light oil, (of which the first and the last por

* We publish this at the request of several subscribers. So far as these specifications refer to the purification of coal oil, they are of course safe rules to follow in the treatment of petroleum. In fact, the most of the knowledge possessed respecting the distillation, &c, of rock oil, is either directly or remotely derived from this patent, together with those obtained by YOUNG and BROWN.-Editor Merchants' Magazine,

tions are sometimes received separately, in which case the first portion only is called naphtha,) comes over at first accompanied more or less with the water, and afterwards the heavy or dead oil which is separated from the light oil by changing the receiver when the distillate begins to sink in the water. Some samples of tar also yield a large quantity of naphthaline, an oil which is solid at ordinary temperatures.

In distilling tar which contains much naphthaline, the last portions of light oil and the first portions of heavy oil will deposit solid matter in cooling. In some tar the naphthaline, together with paranaphthaline, another solid oil, exists in such quantity, that a large proportion of the heavy oil solidifies in cooling. Other samples of tar contain so little naphthaline that no solid matter is deposited, except by the last portions of the oil which are distilled over at the highest temperatures, to which the retorts are generally exposed. The distillation of coal-tar is usually stopped when the oil has ceased to run freely fluid, and a yellow semisolid matter appears. The light oil, or the naphtha alone, is usually rectified from some heavy oil which it contains by distillation, and is more or less purified by treatment with acid, which is usually concentrated sulphuric acid, if the oil be required colorless, and then forms the rectified coal naphtha of commerce; the less volatile part of the light oil, if separated, and the heavy or dead oil, is not rectified usually, but is applied to coarse purposes in which a pure article is not required.

It is known to chemists that the crude oils of coal-tar contain a quantity of oily matters, some of which are acid, and have received names such as carbolic and rosolic acids and others, and some alkaline, which have been called aniline, picoline, pyrrol, &c.; and besides these an oil which, by exposure to the air, becomes converted into a brown resinous matter. The object of the processes of purification of the oils has been to remove these substances. The nature and properties of the neutral oils, some of which constitute the rectified coal naphtha, have not hitherto been known except that they are hydro-carbons, that is, composed of hydrogen and carbon alone, and that the naphtha has been supposed to be a mixture of several such bodies.

I have thought it necessary to state the above facts in order more readily and clearly to define the nature of this part of my invention, which consists of manufacturing certain hydro-carbons and other substances from tar.

In speaking of temperatures, I at all times refer to the centigrade therometrical scale, (known also as that of Celsius,) in which the freezing point of water is marked, 0 degrees, and the boiling point of water, 100 degrees.

If the unrectified light oil of commerce be distilled without water, it generally commences to boil at about 100 degrees, and continues to distil till the temperature of the boiling fluid reaches 200 degrees, or thereabouts; the last portions often become solid as they cool. The rectified naphtha of commerce of the best sort generally commences to boil at about 90 degrees, and a portion of it (which seldom exceeds one-eighth of the entire quantity) distils over before the temperature in the retort reaches 100 degrees; and the temperature gradually rises as the distillation continues till it reaches about 160 degrees, when the retort becomes generally dry. The rectified naphtha does not solidify or deposit crystals on being submitted to a temperature of 20 degrees, (20 degrees be

In

low 0 degrees,) but some samples of the crude naphtha, if so treated, will deposit crystals or solid matters, which consist of naphthaline, and if separated will be found to remain solid at about 20 degrees, and when' fused to boil at about, or somewhere above 200 degrees. I mention these properties to distinguish rectified naphtha from the spirituous substances which I manufacture from naphtha or tar. And here I would state that the supposition which prevails among naphtha makers, that " the strength" of coal naphtha is determinable by its specific gravity in the same way as that of alcoholic or pyroxylic spirits, is entirely fallacious. the first place, strength as applied to these spirits means relative freedom from water, with which they will mix in all proportions, and the specific gravity and volatility of the mixture are respectively in direct and inverse ratio to the amount of water in the mixture; so that the specific gravity is a true index of the strength of such spirits, but the term "strength" can have no corresponding meaning as applied to coal naphtha or spirituous hydro-carbons, which are not capable of dilution with water. In the second place, the specific gravity is no index of the volatility of the naphtha, or of the quantity of the more volatile spirituous substances which it contains beyond certain limits. If the rectified naphtha has a specific gravity above .875 degrees, taking water to be one, it may be considered as a sign that it still contains naphthaline or some other oil, which boils at a temperature above 200 degrees, or some of the impurities which are removable by acids, and so far the specific gravity is a test of the volatility of the naphtha. But the neutral oils and spirituous substances which compose the pure naphtha (that is, when consisting only of hydro-carbons) are all nearly of the same specific gravity, viz., from .85 to .87, and in practice the specific gravity of the naphtha is rarely reduced so low as .86; and in the state of purity in which the spirituous substances are obtained by rectification sufficient for ordinary purposes, I have found the most volatile of them have a greater specific gravity than some of the less volatile, so that the specific gravity is not a true test of the volatility of naphtha; and I state this lest it should be supposed that the spirituous substances which I produce from coal-tar or coal-naphtha are not different from, or not more volatile than ordinary naphtha, because the specific gravity of the spirituous substances manufactured by me may be the same as or even greater than that of ordinary naphtha.

I believe the only perfect test of the relative volatility of such spirituous substances, oils or naphthas, is by comparison of their boiling points, by which I mean the numbers marked by the index of a thermometer, when the sensitive part of such thermometer is immersed in the fluids, whose volatility is required to be known, the fluids being at the time in active ebullition. The boiling point in such matters is never constant unless the fluids be absolutely pure, and such purity is not easy to be attained in practice in the separation of fluids of different volatility when dissolved in each other, as is the case with the oils and spirituous substances in coal-naphtha, and it is found that the boiling point will continually rise as the fluid boils away into vapor. The points to be particularly noted in so ascertaining the volatility of such fluid are, first, the point at which ebullition commences; secondly, the points about which the largest quantity boils off; and, thirdly, that at which the whole has volatilized; and this test is most conveniently applied in a small glass re

tort with a tubule closed by a cork through which a glass mercurial thermometer passes, the bulb of such thermometer being placed below the surface of the fluid which is to be maintained in ebullition. The volatility of hydro-carbons may also be roughly estimated in some cases by placing a few ounces of the fluid in a bottle closed by a cork, through which two tubes of about one-eighth of an inch bore pass, one terminating below, and the other above, the surface of the fluid, on a stream of air being forced through these tubes, entering by the former tube and escaping by the latter, and a lighted match being applied to the orifice of the latter, by observing the magnitude and the proportion of white light in the flame, if any, which appears at the mouth of the tube; and this apparatus I shall call a test bottle," when I subsequently refer to it. And in some cases the non-volatility of hydro-carbons may be ascertained by their non-inflammability at the surface on approach of a lighted match.

I will now proceed to state what are the spirituous substances and oils which I have found in coal-tar, and which I also separate more or less from each other, or manufacture more or less mixed with each other, or with other substances by the methods hereafter described:

First, I have obtained a spirituous substance which is extremely volatile, which boils when pure at about 60 degrees or 65 degrees, does not solidify at 20 degrees, and has a powerful sulphurous or alliaceous smell. This I call Alliole.

Secondly, a spirituous substance which is less volatile than the last, which boils when pure at about 80 degrees, and solidifies at 0 degrees, being the only one of the spirituous substances that can be solidified by a temperature above 20 degrees, having a smell resembling almonds, which I call Benzole.

Thirdly, a spirituous substance which boils at about 110 degrees, and does not solidify at 20 degrees, which I call Toluole.

Fourthly, a less spirituous and rather oily fluid which boils at about 140 degrees, which I call Cumole.

Fifthly, an oil which boils at 170 degrees, which I call Cymole.

The aforesaid spirituous substances and oils are obtained or manufactured chiefly from "light oil," but the Cymole is found also in "heavy oil;" and,

Sixthly, I have found in the heavy or dead oil, an oil which, when pure, boils at about 240 degrees, and is of specific gravity 900, which I call Mortuole.

I now proceed to state how these substances may be obtained, first remarking that I shall describe other properties of some of these spirituous substances and oils when treating of the preparation of each.

(To be continued.)