served by the different mode of attachment of the urea residues exhibited in the formula now put forward. The mode of production from uric acid of allantoine, alloxan, paraban, etc., will be seen by comparison of the preceding formulæ.

Probably uroxanic acid, C, H,N,O,, is represented by No. 1

5

while the oxonic acid of Strecker and Medicus,* C,H,N,O,, produced under similar conditions, but showing by its containing only three atoms of nitrogen that it cannot include two complete urea residues like those of uric acid, may perhaps have the structure of No. 2.

4

The basicity of pseudo-uric acid, C.H.NO,, may be explained by assuming its two urea residues differently attached, and in one of them an atom of hydrogen taking the place of hydroxyl-thus:

4

In xanthine, C,H,N,O,, whose empirical formula differs from that of uric acid only by an atom of oxygen, we have also two dissimilarly attached residues of urea, but the basic hydroxyl disappears altogether and with it the true acid character, while like urea itself xanthine is capable of uniting with metallic oxides as well as with acids.

* Ann. der Chem., clxxv, 230.

This formula (No. 2) may serve to explain the fact that Strecker's di-methyl-xanthine is isomeric, not identical, with theobromine, C,H,N,O,, if we assume the latter to be as in No. 1, and caffeine, C,H,,N,O2, as in No. 2,

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1. Theobromine (weak base).
H-N-H H,C-N-CH3

0 4

2. Caffeine (weak base). H-N-CH, HỌC−N--CH

both urea residues in each of these formulæ being similarly connected with the acid nucleus. The relation to di-methylparaban (cholestrophan) is obvious.

We may probably assume No. 1 as the formula of caffeidine, C,H,,N,O (a stronger base than caffeine).

12 4

Hypoxanthine, C,H,N,O, exhibits the same general character with xanthine, and containing one atom less oxygen may be represented as in No. 2, above.

The above formule for hypoxanthine and xanthine accord well with the reported production by Strecker of the latter from the former by oxidation, and of a mixture of both bases from uric acid by reduction with sodium amalgam.

Passing to the compounds in which two acid residues are united with each other and at the same time with residues of urea, we may formulate oxalantine, C,H,N,O,, as follows:

Oxalantine (neutral).

H-N-H

4

thus directly explaining the relation to paraban, and production therefrom by coalescence of two molecules with elimination of an atom of oxygen (or from a molecule each of oxaluric acid and paraban, with removal of an atom of oxygen and a mole. cule of water).

The union of hydantoine with allanturic acid, with separation of water, gives for allituric acid, C,H,N,O,, the formula No. 1.

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1. Allituric acid (monobasic). 2. Leucoturic acid (monobasic).

and the like union of paraban and allanturic acid leads to No. 2 for leucoturic acid of Schlieper, C,H,N,O,. This last formula explains the possibility at least of a difference between leucoturic acid and oxalantine, the identity of which does not seem clearly established.

In each of the last two cases we have one ureic residue inverted as regards its mode of attachment to the acid nucleus when the coalescence takes place.

Two molecules of (dibasic) barbituric acid unite with separation of a molecule of water, giving rise to di-barbituric acid, C,H,N,O,, with unchanged basicity,

8

6

4

while the union of a molecule of barbituric acid and [one of dialuric acid, with inversion of the ureic residue of the latter and elimination of a molecule of water, gives us hydurilic acid, C.H ̧N,O., (No. 2).

8

6 4

Alloxantine, C,H,N,O,, may be represented as

8

4

4

clearly exhibiting the analogy of this body to oxalantine, and its production in a similar way by the coalescence of two molecules of alloxan with separation of oxygen (or a molecule of alloxan and one of dialuric acid with the additional separation of water). The formula of Gibbs for alloxantine would seem to imply that it is a monobasic acid (or, according to the exact terms of his own definition,* tribasic).

8

Finally, it is difficult to suggest with confidence a formula for the problematical substance murexide, C,H,N ̧O... If an amide character be admitted for it; and it does seem that evidence is still wanting to conclusively prove that it is an ammonium salt, especially in view of non-production of purpuric acid and the undoubted existence of isomeric iso-purpurates (and possibly other salts) which may have led to an undue assumption of identity of type between murexide and its metallic derivatives; we may perhaps assume this substance to have the formula No. 1,

in which the union of two molecules of dialuramide is effected, with elimination of hydrogen, by the linking together of the ureic carbon atoms. This view of the constitution of murexide (making it alloxantine-amide) obviously affords a simple explanation of its production from dialuramide by oxidation, from ammonium dialurate by heating, from alloxantine and alloxan by the action of ammonia, &c., and also suggests the probable

Loc. cit.,-"cyanyl may be regarded as the acidifying term. Its quantity, therefore, determines the basicity of the acid."

ease with which isomeric changes may be brought about. If murexide be ammonium purpurate, the formula might perhaps be changed to the form in No. 2.

While the views above stated as to the structure of the numerous and interesting compounds derivable from urea and uric acid are liable to objection at sundry minor points, and in several instances other arrangements of the elements might be adopted without interference with the main idea, I believe that on the whole the constitutional formulæ set forth in this paper more nearly represent the present state of our knowledge of this group than any others which have been proposed, and especially possess the advantage of better explaining the chemical character or function of the substances referred to,* while at least equally well exhibiting the nature of the changes by which they are produced from each other.

University of Virginia, Nov. 4, 1875.

ART. XXXVII-On the Evidences of horizontal crushing in the formation of the Coast Range of California; by JOSEPH LECONTE.

[Read before the National Academy of Sciences, November, 1875.] Ir will be remembered that in a former paper "On the formation of the greater inequalities of the earth's surface,"t I sustained the view that mountain ranges are formed wholly by a yielding of the crust of the earth along certain lines to horizontal pressure; not, however, a yielding by bending of the crust into a convex arch, filled and sustained by a liquid beneath, as has been supposed by some; but by a crushing or mashing together horizontally of the whole crust, with the formation of close folds and a thickening or swelling upward of the squeezed mass. I believe the structure of all mountain ranges, in which the stratification has not been obscured by metamorphism, would demonstrate this mode of formation.

I have long thought that the Coast Range in this vicinity is peculiarly adapted to exhibit in its structure the mode of its formation. It is destitute of granite axes, and it has been but little, in many places not at all, changed by metamorphism or overlaid by igneous ejections. A good section ought to clearly reveal its structure and its structure ought no less clearly to reveal the mode of its formation.

With this conviction, on the 5th of January last, in company

* The formula of Baeyer (in common with all those representing urea as carbamide) seem to fail in securing this advantage, although involving in part the

same sort of view of the ureides as that above stated.

+ This Journal, III, vol. iv, pp. 345 and 460.