could never have arisen among an unintellectual and half-barbarous people. So perfect a work implies many preceding less perfect works which have disappeared. It marks the culminating point of an ancient civilization, of the early stages of which we have no record whatever.

The three cases to which I have now adverted (and there are many others) seem to require for their satisfactory interpretation a somewhat different view of human progress from that which is now generally accepted. Taken in connection with the great intellectual power of the ancient Greeks-which Mr. Galton believes to have been far above that of the average of any modern nation-and the elevation, at once intellectual and moral, displayed in the writings of Confucius, Zoroaster, and the Vedas, they point to the conclusion, that, while in material progress there has been a tolerably steady advance, man's intel lectual and moral development reached almost its highest level in a very remote past. The lower, the more animal, but often the more energetic types, have however always been far the more numerous; hence such established societies as have here and there arisen under the guidance of higher minds, have always been liable to be swept away by the incursions of barbarians. Thus in almost every part of the globe there may have been a long succession of partial civilization, each in turn succeeded by a period of barbarism; and this view seems supported by the occurrence of degraded types of skull along with such as might have belonged to a philosopher"—at a time when the mammoth and the reindeer inhabited southern France.

Nor need we fear that there is not time enough for the rise and decay of so many successive civilizations as this view would imply; for the opinion is now gaining ground among geologists that paleolithic man was really preglacial, and that the great gap-marked alike by a change of physical conditions, and of animal life-which in Europe always separates him from his neolithic successor, was caused by the coming on and passing away of the great ice age.

If the views now advanced are correct, many, perhaps most, of our existing savages, are the successors of higher races; and their arts, often showing a wonderful similarity in distant continents, may have been derived from a common source among more civilized peoples.

I must now conclude this very imperfect sketch of a few of the offshoots from the great tree of Biological study. It will, perhaps, be thought by some that my remarks have tended to the depreciation of our science, by hinting at imperfections in our knowledge and errors in our theories, where more enthu siastic students see nothing but established truths. But I trust that I may have conveyed to many of my hearers a different

impression. I have endeavored to show that even in what are usually considered the more trivial and superficial characters presented by natural objects, a whole field of new inquiry is opened up to us by the study of distribution and local conditions. And as regards man, I have endeavored to fix your attention on a class of facts which indicate that the course of his development has been far less direct and simple than has hitherto been supposed; and that, instead of resembling a single tide with its advancing and receding ripples, it must rather be compared to the progress from neap to spring tides, both the rise and the depression being comparatively greater as the waters of true civilization slowly advance towards the highest level they can reach.

And if we are thus led to believe that our present knowledge of nature is somewhat less complete than we have been accustomed to consider it, this is only what we might expect; for however great may have been the intellectual triumphs of the nineteenth century, we can hardly think so highly of its achievements as to imagine that, in somewhat less than twenty years, we have passed from complete ignorance to almost perfect knowledge on two such vast and complex subjects as the origin of species and the antiquity of man.

SCIENTIFIC INTELLIGENCE.

I. CHEMISTRY AND PHYSICS.

In the

1. On the Pyrogenic Hydrocarbons in Coal Gas.-BERTHELOT has made a study of the hydro-carbons in coal gas, which tends to confirm his theory of the formation of these bodies by the action of acetylene and hydrogen at high temperatures. Paris gas for example, he finds that he can detect benzene by exposing two or three cubic centimeters to a drop of fuming nitric acid. On diluting with water, the characteristic odor of nitrobenzene appears. Fifty liters of gas passed through 8 or 10 c.c. of the acid, gives enough nitrobenzene when diluted, to weigh; from which it appears that the gas contains two or three volumes of benzene vapor in the hundred. More accurate determination gives 3 to 35 volumes. Next to methane, therefore, benzene is the principal hydrocarbon in this gas and is the illuminant, par excellence. Ethylene and acetylene, though present, exist in minute proportion, only two to three thousandths. Propylene, butylene, and allylene are found, in amount about two-tenths per cent. They were detected by passing the gas first through sulphuric acid diluted with its own volume of water, and then through a column of pumice stone wet with concentrated sulphuric acid. A tarry substance collected in the first vessel, which yielded AM. JOUR. SCI.-THIRD SERIES, VOL. XII, No. 71.-Nov., 1876.

no products volatile below 360°-400°, and was probably composed of polymers of some easily alterable hydrocarbon. The acid itself, fractionated, gave acetone, 0-25 gram per 100 cubic meters, coming from the hydration of allylene. The sulphuric acid collected beneath the pumice column gave two layers. The lower one consisted of the acid, more or less altered. Diluted with water, a tarry substance of high boiling point separated, probably polymerized hydrocarbons. The acid liquid gave isopropyl alcohol on distillation, thus proving the existence of propylene. The upper layer of liquid, in amount about 25 grams to 100 cubic meters of gas, consisted of hydrocarbons, and gave on fractioning, benzene (with a little toluene) 2 per cent, mesitylene (C,H12) 5 per cent, cymene (CH4) 20 per cent, tricrotonylene (C2H,g) 30 per cent, colophene (CH) 32 per cent, residue fixed at 320° 5 per cent, intermediate products and loss 6 per cent 100. In one million volumes of this gas, consequently, there are by this analysis:

Н

30000 to 35000

1000 (about) 1000 to 2000

2.5

Allylene (C,H,)

Butylene (CH) and analogues

Crotonylene (CH)

Terene (CH)

Hydrocarb's transfor'd into fixed polymers, est'd 83
Diacetylene and analogous hydrocarbons, est'd 15

6 6

2

The author regards these products as derived according to the reactions upon which he founds his theory, from the four fundamental hydrocarbons acetylene C2H2, ethylene C2H1, dimethyl C2H, and methane CH4. These, together with hydrogen forming a system in equilibrium, such that, at a red heat they are all formed from any one of them as the starting point. Thus from methane comes directly ethylene (C2H,) or (CH2)2, propylene (CH2), and the series of polymers (CH) Acetylene produces benzene CH, or (CH2), and the series of polymers (CH2), Moreover, from the union of two of these fundamental hydrocarbons, more complex bodies come: acetylene and benzene giving styrolene C.H.; acetylene and styrolene, naphthalene C1H.; acetylene and naphthalene, acenaphthene C,2H10; and styrolene and benzene, anthracene C,,H... So acetylene combines at a dull red heat with ethylene to form ethylacetylene CH, and with propylene to yield propylacetylene C,H,, the former identical with crotonylene, the latter with terene. The uselessness of the present eudiometric method of determining the illuminants in gas analysis is obvious from these results.-Bull. Soc. Ch., II, xxvi, 104, Aug., 1876.

8

14 10

10

G. F. B.

2. Occurrence of Benzene in Rosin Oil.-WATSON SMITH has examined the light oils obtained as a bye-product in the refining

In

of rosin by distillation in a current of super-heated steam. 1867, he examined a sample which began to boil at 50° and which distilled almost completely below 100°. On fractioning, a liquid was obtained boiling between 80° and 85° which had the properties of benzene, though contaminated with turpentine-products. Meantime changes had been made in the works, a much higher temperature being employed. A sample from the first run of the rectifying still, examined in 1875, began to boil at 109°, and to condense at 116°. When fractionated, toluene was the substance of lowest boiling point obtained. Hence the temperature of distillation determines the products.-J. Chem. Soc., II, xxx, 29, July, 1876.

7 5

G. F. B.

2

3. On the Constitution of the Benzene Derivatives.-WROBLEWSKY described in 1875 two metabromtoluenes having identical properties, in one of which the methyl and the bromine atoms occupied the 1: 3 position according to Kekulé's theory, in the other the 1:5 position. He now describes two ortho-toluidines having the methyl and amidogen groups respectively in the positions 1:2 and 1:6. Starting with dibromparatoluidine, in which the two bromine atoms occupy the positions 3 and 5, the methyl and amidogen groups 1 and 4, the author replaced the amidogen by iodine, thus forming C, H, Br, I, dibromparaiodtoluene. By the action of fuming nitric acid a nitroderivative C, H, Br2INO2 was obtained, in which the nitryl must occupy the position 2 or the position 6. On reduction with tin and hydrochloric acid this gave CH ̧Br2INH2, and this by the action of sodium amalgam gave orthotoluidine, C,H,NH,. For the second substance, the metadibrom-paraiod-ortho-toluidine was converted by the method of Griess into C, H, Br2I, dibrom-diiod-toluene. This gave a nitroderivative C,H,Br2INO,, in which the nitryl must occupy the position 6 if the former had 2; or the reverse. By reducing the amido-product obtained from this with sodium amalgam, a second ortho-toluidine was obtained, identical in properties with the former, thus adding a new confirmation to Kekulé's theory. The progress of the replacements is thus represented:

3

4

22

2

-Ber. Berl. Chem. Ges., ix, 1055, July, 1876.

G. F. B.

4. On the Action of Malt-extract on Starch.-O'SULLIVAN bas examined more fully the conditions under which malt-extract acts on starch. He formulates his conclusions as follows: (1) Maltose and dextrin are the only products of the action of malt-extract on starch. (2) Cold malt-extract does not act on ungelatinized starch. (3) Malt-extract begins to dissolve starch at the temperature of gelatinization or a few degrees lower. (4) Malt-extract dissolves gelatinized starch in the cold, (10° to 20°) almost completely if the gelatinization be perfect. (5) When starch is dissolved by malt-extract at any temperature below 63°, if the solution be immediately (5 or 10 minutes) cooled and filtered, the product invariably contains maltose and dextrin in proportions agreeing closely with 67.85 per cent of the former, and 32.15 per cent of the latter. (6) If the temperature of the action be between 64° and 68°-70°, the maltose present is 34.54 per cent and the dextrin 65′46 per cent. (7) If the temperature be between 68° and 70° and the point at which the activity of the transforming agent is destroyed, the maltose and dextrin are in the proportion of 174 to 82.6 per cent. The decomposition of starch into maltose and dextrin is molecular and takes place according to three equations, corresponding to the conditions in (5), (6) and (7) above. Dextrin is converted into maltose by a slow and gradual process of hydration. -J. Chem. Soc., xxx, 125, Aug., 1876.

G. F. B.

5. Detection of Carbamic acid in Animal fluids.-HOFMEISTER has examined the evidence upon which Drechsel based his assertion that carbamic acid is produced wherever nitrogenous substances are oxidized in alkaline solutions, and hence exists in the blood. He finds that the reactions upon which Drechsel based his opinion are untrustworthy, inasmuch as the production of a precipitate on boiling, after having filtered off the precipitate produced by calciuin nitrate, cannot be taken as proof of the existence of carbamic acid. J. pr. Ch., II, xiv, 173, Aug., 1876. G. F. B.

6. Friction of Gases.-M. WIEDEMANN has measured the changes in the coefficients of friction of gases with changes in the temperature by a new form of apparatus. In a recent paper on the specific heat of gases he claims that a gas undergoes a sort of dissociation upon a change of temperature and that the diameter of the molecules ought not to vary with the temperature according to the same law as if the gas was not decomposed. Moreover, according to the new theory of gases, the coefficient of friction of gases gives a relative measure of the diameter of its molecules. The gas is contained in two glass bulbs 7.3 cms. in diameter and and 4.5 cms. high. One is placed above the other and they are connected by a glass tube 8 cms. in diameter and 15 cms. long. They are enclosed in a case with glass sides which may be filled with water. Each bulb contains in the prolongation of the tube connecting them, a small orifice. To the lower one is connected a three-way cock with two horizontal tubes. One of these tubes is connected with a reservoir of mercury of variable height, by which mercury may be admitted into the bulbs. The other tube