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calcium carbonate, filtered, and treated with an equal volume of alcohol. After twelve hours the greater part of the calcium salt had completely separated. At first the author supposed this to be calcium glycerate in a pure form; but by solution in warm water it left a residue, which only dissolved by long boiling. This residue, abont a tenth part of the entire salt in amount, was filtered off, washed, and dried. It appeared as a white powder, non-crystalline. Upon analysis this powder gave numbers agreeing very closely with calcium tartronate. Conversion into the acid confirmed this supposition. Under the glass the acid crystallized in tables having the form of the tartronic acid from nitro-tartaric acid. This view was confirmed by the results of its elementary analysis. —35 C, VIII., 1456, Nov., 1875.

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ACTION OF WEAK ACIDS ON SALTS OF STRONGER ONES.

The importance in chemical dynamics of the question, What is the condition in which several substances exist when in solution ? has been oftener recognized than experimentally investigated. Bergmann advanced long ago the theory that is now generally maintained, i, e., that universally bodies combined according to the strength of their chemism. Berthollet, on the other hand, asserted that when different salts were dissolved together, as many bodies were formed as by the exchange of acids and bases were possible. Among the experiments made to settle the question, those of Betten. dorff are perhaps the most satisfactory. By studying the action of light on certain solutions, he was led to decide for the view of Bergmann. Hübner and Wiesinger, not regarding these experiments of Bettendorff as sufficiently numerons or comprehensive, have made use of a different method for solving the problem by making the distinct proposition: Can a dissolved acid expel a stronger one from its salts in solution without any substance separating from the solution? For these experiments they used benzoic acid for the weaker and nitrobenzoic acid for the stronger acid. They are both monobasic, are easily obtained pure, are easily separated from each other and from their salts, and can be recognized with certainty. They differ only apparently in the strength of their chemism. In the qualitative experiments, barium nitrobenzoate and free benzoic acid were dissolved

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in a large excess of water, the solution being heated to 80°
Centigrade. After cooling to 14°-17°, the solution contain-
ed not only the substances originally dissolved, but also free
nitrobenzoic acid and barium benzoate. The nitrobenzoic
acid set free in the reaction, together with the benzoic acid
also present, was dissolved by agitation with chloroform or
benzene, in which the barium salt is insoluble. In the resi-
due, after the solvent was distilled off, the presence of nitro-
benzoic acid was proved by means of sodium.
titative experiment, 1.6592 grammes of pure barium nitro-
benzoate was mixed with the theoretical quantity 1.1815
grammes of pure benzoic acid, and dissolved in an excess
of hot water. The nitrobenzoic acid obtained from the
solution was 0.2341 grammes, being 19.81 per cent. of the
whole quantity. Additional experiments seem to show
that the quantity of the stronger acid set free depends on
that of the weaker.—35 C, VIII., 466, April, 1875.

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COPPER IN THE HUMAN BODY.

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Not long since, in a case of suspected poisoning by a salt of copper, upon analysis a large percentage of metallic corper was found in the liver and kidneys. Subsequent research, however, proved that copper usually exists as a normal constituent of the animal body, the investigation having taken place upon fourteen human subjects from the French hospitals. Portions of these were first dried, then carbonized, and the ashes treated for copper, the amount of which varied in quantity from 1 to 1} milligrammes. The same metal has even been found in the liver of the human fætus.-13 B, Feb. 20, 1875, 186.

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RELATIVE AMOUNTS OF POTASH AND SODA IN MILK AND

OTHER FOOD, AND IN THE ENTIRE BODY. In pursuing the investigation of the value of salt in nutrition, Bunge was led to determine the amount of the alkalies and of chlorine in the most important articles of food, especially in milk; and, in this connection, the amounts of the alkalies and of chlorine in the entire bodies of a number of animals was also ascertained. Besides analyses of human milk, and of that of herbivorous and carnivorous animals, analyses were also made of the entire bodies of a mouse,

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four cats, two young dogs, two young rabbits, five rabbit embryos, and of a number of butterfly chrysalides, and the amount of soda and of potash in different articles of food was found. From the numbers thus obtained, and given in tabular form, iuteresting conclusions were drawn, in regard to the relation existing between the food and the composition of the body, as regards the amount of the alkalies and chlorine present.

In vegetable food the excess of potash over soda, compared by equivalents, is much greater than in human milk, or those in that of herbivorous animals; so that, if the proportions of potash and soda in milk are to be considered as the most favorable to nutrition, the addition of salt to all the more important vegetable articles of food is indicated. The amount of soda in the organism varies within as wide limits in the animal kingdom as in the vegetable, and the amount of soda, potash, and chlorine in milk is not constant, but varies with the food and other conditions. The young of the carnivorous animals receive in their milk potash and soda, and generally all the fixed ingredients, in almost the same proportions required for their growth; and while in the bodies of the young of herbivorous animals the relative amounts of soda and potash are found to differ from those of the carnivorous animals, relative amounts of these substances secreted in the milk by which they are nourished conform to this difference. Prolonged feeding, however, upon substances rich in potash and poor in soda will increase the relative amount of the former in the milk.-19 C, Jan. 23, 1875, 35.

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E. MINERALOGY AND GEOLOGY.

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POT-HOLES, OR GIANT KETTLES." It is not always that geological investigations have as their object phenomena which are of general interest, and with which all are more or less familiar. This is certainly the case, however, with the study of the "giant kettles" in the neighborhood of Christiania, Norway, which has been lately carried on by Professor Kjerulf and some of his students. There is hardly a running stream in our country of any considerable size which does not give proof of the power of water and stones in motion in what are popularly called “potholes.” An eddy in the stream where the current is strong sets a few pebbles in revolution. These commence a depression, into which larger stones fall, and the grinding is continued until a cavity has been produced perhaps several feet in depth, and almost perfectly round. These are often to be observed, not only in stream beds, but also in rocks on the sea-shore, where the rush of the tide must supply the motive force.

The famous "giant kettles” of Norway are simply “potholes" on a larger scale, and produced in former times under somewhat different conditions than we have at present. The superstition of the people represents them as having been made by giants. In some places, where the form is oblong and irregular, fancy has seen in them the footprints of these monsters, while in one place, where the road goes directly through a very large kettle, the saying is that there St. Olaf turned his horse around. On the west coast of Norway another name is used, and they are spoken of as giants' chairs.

The description of one of these kettles examined by Professor Kjerulf will give some idea as to their size and general character. At the surface it had a diameter of about eight feet, being slightly elliptical in form. It widened considerably on the descent, and then contracted again at the bottom. It is interesting to note that the walls were distinctly worked out in a spiral, which could be traced from top to

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bottom. In the case of some other kettles examined, the spiral was so perfect that the cavity could be compared to the impression of a gigantic snail.

The total depth of the kettle in question from the highest point of the margin was forty-four feet, the axis inclining somewhat toward the west. It was filled, as is always the case, with gravel and broken rock, though toward the bottom numerous so-called grinding-stones were found, some of them 300 pounds in weight, and all smooth and elliptical in shape. It was through their revolution that the excavation bad been made. It required three men, working for fifty days, to clear this giant kettle of its contents, and the whole amount taken out was estimated at 2350 cubic feet, some of the stones being so large that they had to be mined before they could be hoisted out.

The kettles, in general, present much the same features as the one which has been just described, though there is a great variation in ratio of width to depth, many of them being shallow, larger at the top than at the bottom, and very properly are called kettles, while others, as the one alluded to, are deep, and could better be called wells. It is to be observed that they are by no means necessarily found in present river channels. They are most common in the neighborhood of the great fiords, though they have been observed too at a height of 1200 feet above the sea. In regard to their origin, the best authorities refer it to the time when the land was covered by enormous glaciers, such as now exist in the upper part of Greenland. The melting of the ice on the surface of glaciers gives rise to considerable rivers, and as these find some crevice in the ice, they descend with violence, and it is conceivable that such a stream striking the bed rock below might be the means, with the masses of rock they would put in motion, of producing the enormous cavities which are now observed. This theory, as carried out by its supporters, meets with some difficulties, but seems to be the best which has been proposed.

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PROBABLE AGE OF THE CRYSTALLINE ROCKS OF THE SOUTII

ERN APPALACHIANS, Professor Bradley, of Knoxville, Tennessee, has recently published the results of his geological labors among the

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