The

the very best intentions in the matter. facts were too much for us; and all we can do now is to apologise for ourselves and for the gas.

Several questions may be asked, upon which I should like to say a word or two, if you will allow me to detain you a little longer. The first question (I do not know whether I need ask it) is, have we got hold of a new gas at all? I had thought that that might be passed over, but only this morning I read in a technical journal the suggestion that argon was our old friend nitrous oxide. Nitrous oxide has roughly the density of argon; but that, as far as I can see, is the only point of resemblance between them.

Well, supposing that there is a new gas, which I will not stop to discuss, because I think the spectrum alone would be enough to prove it, the next question that may be asked is, is it in the atmosphere? This matter naturally engaged our earnest attention at an early stage of the enquiry. I will only I will only indicate in a few words the arguments which seem to us to show that the answer must be in the affirmative.

In the first place, if argon be not in the atmosphere, the original discrepancy of densities which formed the starting point of the investigation remains unexplained, and the discovery of the new gas has been made upon a false clue. Passing over that, we have the evidence from the blank experiments, in which nitrogen originally derived from chemical sources is treated either with oxygen or with magnesium, exactly as atmospheric nitrogen is treated. If we use atmospheric nitrogen we get a certain proportion of argon, about 1 per cent.

If we

treat chemical nitrogen in the same way we get, I will not say absolutely nothing, but a mere fraction of what we should get had atmospheric nitrogen been the subject. You may ask, why do we get any fraction at all from chemical nitrogen? It is not

difficult to explain the small residue, because in the manipulation of the gases large quantities of water are used; and, as I have already explained, water dissolves argon somewhat freely. In the processes of manipulation some of the argon will come out of solution, and it remains after all the nitrogen has been consumed.

Another wholly distinct argument is founded upon the method of diffusion introduced by Graham. Graham showed that if you pass gas along porous tubes you alter the composition, if the gas is a mixture. The lighter constituents go more readily through the pores than do the heavier ones. The experiment takes this form. A number of tobacco pipes-eight in the actual arrangement-are joined together in series with india rubber junctions, and they are put in a space in which a vacuum can be made, so that the space outside the porous pipes is vacuous or approximately so. Through the pipes ordinary air is led. One end may be regarded as open to the atmosphere. The other end is connected with an aspirator so arranged that the gas collected is only some 2 per cent. of that which leaks through the porosities. The case is like that of an Australian river drying up almost to nothing in the course of its flow. Well, if we treat air in that way, collecting only the small residue which is less willing than the remainder to penetrate the porous walls, and then prepare nitrogen' from it by removal of oxygen and moisture, we obtain a gas heavier than atmospheric nitrogen, a result which proves that the ordinary nitrogen of the atmosphere is not a simple body, but is capable of being divided into parts by so simple an agent as the tobacco pipe.

If it be admitted that the gas is in the atmosphere, the further question arises as to its nature.

At this point I would wish to say a word of explanation. Neither in our original

announcement at Oxford, nor at any time since, until the 31st of January, did we utter a word suggesting that argon was an element; and it was only after the experiments upon the specific heats that we thought that we had sufficient to go upon in order to make any such suggestion in public. I will not insist that that observation is absolutely conclusive. It is certainly strong evidence. But the subject is difficult, and one that has given rise to some difference of opinion among physicists. At any rate, this property distinguishes argon very sharply from all the ordinary gases.

One question which occurred to us at the earliest stage of the enquiry, as soon as we knew that the density was not very different from 21, was the question of whether, possibly, argon could be a more condensed form of nitrogen, denoted chemically by the symbol N3. There seem to be several difficulties in the way of this supposition. Would such a constitution be consistent with the ratio of specific heats (1.65)? That seems extremely doubtful. Another question is, Can the density be really as high as 21, the number required on the supposition of N3? As to this matter, Professor Ramsay has repeated his measurements of density, and he finds that he cannot get even so high as 20. To suppose that the density of argon is really 21, and that it appears to be 20 in consequence of nitrogen still mixed with it, would be to suppose a contamination with nitrogen out of all proportion to what is probable. It would mean some 14 per cent. of nitrogen, whereas it seems that from one-and-a-half to two per cent. is easily enough detected by the spectroscope. Another question that may be asked is, Would N, require so much cooling to condense it as argon requires?

3

There is one other matter on which I would like to say a word-the question as to what N3 would be like if we had it.

3

3

There seems to be a great discrepancy of opinions. Some high authorities, among whom must be included, I see, the celebrated Mendeleef, consider that N, would be an exceptionally stable body; but most of the chemists with whom I have consulted are of opinion that N, would be explosive, or, at any rate, absolutely unstable. That is a question which may be left for the future to decide. We must not attempt to put these matters too positively. The balance of evidence still seems to be against the supposition that argon is N,, but for my part I do not wish to dogmatise.

A few weeks ago we had an eloquent lecture from Professor Rücker on the life and work of the illustrious Helmholtz. It will be known to many that during the last few months of his life Helmholtz lay prostrate in a semi-paralyzed condition, forgetful of many things, but still retaining a keen interest in science. Some little while after his death we had a letter from his widow, in which she described how interested he had been in our preliminary announcement at Oxford upon this subject, and how he desired the account of it to be read to him over again. He added the remark: "I always thought that there must be something more in the atmosphere."

LLOYD MORGAN UPON INSTINCT.

IN the last number of Natural Science

Professor C. Lloyd Morgan gives a valuable synopsis of the various definitions of instinct which have been proposed by Darwin, Wallace, Romanes, James, Spencer and other writers upon this subject. He shows that surprisingly wide differences of opinion prevail and concludes that, “Since the question of origin is still sub judice, the definition should be purely descriptive, so as not to prejudge this question. And since the phenomena of instinct can only be rightly understood in their relation to automatism connate and acquired, to im

pulse, to imitation and to intelligence, our definition of instinctive activities should find a place in a scheme of terminology." He sets forth such a scheme sending us in MSS. a number of additions and modifications which are embodied in the following table and abstract:

"It may be premised:

1. That the terms congenital and acquired are to be regarded as mutually exclusive. What is congenital is, as prior to individual experience, not acquired. What is acquired is, as the result of individual experience, not congenital.

2. That these terms apply to the individual, whether what is acquired by one individual may become congenital through inheritance in another individual, is a question of fact which is not to be settled by implications of terminology.

3. That the term acquired does not exclude an inherited potentiality of acquisition under the appropriate conditions, such inherited potentiality may be termed innate. What is acquired is a specialization of a vague and general innate potentiality.

4. That what is congenital and innate is inherent in the germ plasm of the fertilized

ovum.

Congenital Movements and Activities: Those the performance of which is antecedent to individual experience; they may be performed either (a) at or very shortly after birth (connate) or (b) when the organism has undergone further development (deferred).

Congenital Automatism: The congenital physiological basis of those movements or activities which are antecedent to individual experience.

Physiological Rhythms: Congenital (or connate) rhythmic movements essential to the continuance of organic life.

Reflex Movements: Congenital, adaptive and coördinated responses of limbs or parts of the body; evoked by stimuli.

Random Movements: Congenital, more or less definite, but not specially adaptive movements of limbs or parts of the body; either centrally initiated or evoked by stimuli.

Instinctive Activities: Congenital, adaptive and coördinated activities of the organism as a whole; specific in character, but subject to variation analogous to that found in organic structures; similarly performed by all the members of the same more or less restricted group, in adaptation to special circumstances frequently recurring or essential to the continuance of the race; often periodic in development and serial in character.

Mimetic Movements and Activities: Due to individual imitation or similar movements or activities performed by others.

Impulse (Trieb): The affective or emotional condition, connate or acquired, under the influence of which a conscious organism is prompted to movement or activity, without reference to a conceived end or ideal.

Instinct: The congenital psychological impulse concerned in instinctive activities. Control: The conscious inhibition or augmentation of movement or activity.

Intelligent Activities: Those due to individual control or guidance in the light of experience through association.

Motive: The affective or emotional condition under the influence of which a rational being is guided in the performance of deliberate acts.

Deliberate Acts: Those performed in distinct reference to a conceived end or ideal. Habits Organized groups of activities, stereotyped by repetition, and characteristic of a conscious organism at any particular stage of its existence.

Acquired Movements, Activities or Acts: Those the performance of which is the result of individual experience. Any modifications of congenital activities which result from experience are so far acquired.

Acquired Automatism: The individually modified physiological basis of the performance of acquired movements or activities which have been stereotyped by repetition."

Professor Morgan points out that there is some overlap in these definitions, but it is difficult to see how such overlaps are to be avoided. H. F. O.

SOME MEANDERING RIVERS OF WISCONSIN.

Two years ago Professor Davis* called attention to the wide meanders of the Osage river of Missouri. He said: "The meanders of the river are peculiar in not being like those of the Mississippi, spread upon a flat flood-plain. High spurs of the upland occupy the neck of land between every turn of the stream. Evidently the meanders are not of the ordinary kind." He explained the peculiar tortuous course of the river as an inheritance from an earlier cycle, during which the river had worn the land down to a surface of faint relief. The stream at that time swung to and fro in broad meanders developed on a wide flood-plain. The whole region was then somewhat elevated, and the stream again set to work to cut down its channel to the new baselevel. But the meandering course which it had acquired late in the preceding cycle was carried over into the new cycle of its life.

A recent visit to a part of the driftless area of Wisconsin, Lafayette and Grant counties, gave me an opportunity of observing a similar habit of some of the rivers of that region. The general surface of the country is that of a gently rolling plain, at an elevation of from 850 to 1000 feet, A. T. The interstream surfaces are broad and slightly undulating, but well drained. The surface rock, except in the immediate vicinity of the streams, is the Galena limestone. Occasionally the general level of the top of the country is

*SCIENCE, April 28, 1893, vol. xxi., p. 225 et seq. SCIENCE, November 17, 1893, vol. xxii., p. 276 et seq.

broken by hills, which rise 200 to 300 feet above the general level. The highest of these are capped by the hard Niagara limestone; the lower by beds of the Cincinnati group. These hills form the so-called 'mounds,' of which, in the area visited, the Platte Mounds-1250-1300 feet, A. T.—are the highest. The hard Niagara limestone caps of these mounds are the remnants of beds which formerly stretched over all this region, and which has since been removed by denudation. To hills of this type Prof. Davis has given the name, Monadnocks.

The rocks of this region are nearly horizontal, and in general there is not a sharp contrast between the slant of the beds and the general slope of the upland surface. It seems, therefore, as if the upland might be a structural plain due to a resistant stratum, the Galena limestone, at the level of the upland-a stratum which had been revealed by denudation of the overlying beds. If this were the case, the upland level would be independent of any former baselevel. But such a conclusion does not seem to be admissible; although nearly horizontal, the limestone has been bent into gentle flexures, some of which are sufficient to bring the underlying Trenton limestone and St. Peter's sandstone up to the level of the upland surface. The plain is continuous across these low arches and bevels the edges of the gently inclined beds. Moreover, to the north of the outcrop of the Galena limestone, the upland plain bevels the gently inclined edges of the underlying formation, which there come to the surface. In that region, however, the plain is now more completely dissected than further south.

Whatever correspondence exists between the inclination of the beds and the slope of the plain is fortuitous and not due to structure primarily. It is believed that this plain is a surface of denudation, the result of long continued erosion on a greater land mass when the land stood lower

than at present. The upland surface is believed to be an elevated peneplain.

It is now moderately dissected by valleys which along the larger rivers are from 100 to 200 feet deep. In comparison with the width of the gently undulating interstream surfaces these valleys are not very wide. The slopes are quite steep and locally form bluffs, but towards the top they pass by a graceful curve into the almost level upland. The present flood-plains along the bottoms of the valleys are generally from an eighth to a quarter of a mile in width. In terms of development the present valleys are well on towards maturity. The sharp narrow valleys of extreme youth are entirely absent. The rivers have made considerable progress in the present cycle in reducing the land mass to the level dependent on the grade of their channels, but the amount of work still to be done is vastly in excess of what has already been accomplished.

The three topographic features mentioned, namely, the broad undulating upland, with an elevation of from 850 to 1,000 feet; the few monadnocks rising above it, and the valleys cut into it, give a clue to the stages of geographic development of this region. The upland peneplain is a surface of denudation produced by long continued erosion, when the land mass stood lower than at present.

This cycle of erosion lasted a long time and the baseleveling was almost completed. Very few monadnocks rose above the general plain. The cycle was ended by an uplift, which quickened the streams, restored to them their cutting powers, and compelled them to erode new valleys in the old peneplain. They have now cut down their channels until their ability to transport material is just about equal to the material which they have to carry. Rivers, the profiles of whose streamchannels are in this condition of equilibrium, have been called by Davis (SCIENCE, N. S., Vol. I., p. 176) graded rivers. The differ

ence in the slope of the valley sides and the upland plain indicates a change of level before the excavation of the valleys and after the formation of the upland plain. The process by which the valleys are being formed is not a direct continuation of the process by which the gentle upland slopes were fashioned. The valleys were cut in the upland surface after it was elevated from the low position which it had during its formation.

Confirmatory evidence for this hypothesis is found in the winding courses of the valleys which now dissect this upland. Fever river was studied in the field, and the topographical atlas of the Wisconsin. Geological Survey shows that the Platte, Little Platte, Grant and Pecatonica rivers have this same habit. If the geographical development of this region was as outlined above, the streams at the close of the earlier cycle must have possessed wide, flat valleys, with broad flood-plains, in which they meandered freely. The elevation of the land would have caused the streams to degrade their channels rapidly. In many cases the meanders on the flood-plain would have been superimposed upon the rock below, as the river bed was lowered. The valleys cut in the elevated peneplain would thus come to to preserve, and, as pointed out by Winslow, also increase the meanders of the earlier cycle.

Such seems to have been the case with the Fever river. Its meanders have an average radius of a little less than half a mile, but they are by no means constant. Rock spurs of the upland project into each curve. The slopes on these spurs are generally gentler than on the outside of the curves, where the stream is often undercutting the base of the slope and increasing the meanders. Both open and close oxbows occur. The most marked of the close type of meanders was noted near Benton, where the river makes an almost closed sig