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replaces that suture by extending from the root of the nose to the coronal suture. To keep these compresses in place, a bandage was carried over them from the base of the occiput obliquely forwards; and then, in order to confine the lateral portions of the skull, the same bandage was continued by another turn over the top of the head, immediately behind the coronal suture, and probably with an intervening compress; and the bandaging was repeated over these parts until they were immovably confined in the desired position.

Every one who is acquainted with the pliable condition of the cranial bones at birth, will readily conceive how effectually this apparatus would mould the head in the elongated or cylindrical form ; for, while it prevents the forehead from rising, and the sides of the head from expanding, it allows the occipital region an entire freedom of growth; and thus without sensibly diminishing the volume of the brain, merely forces it into a new though unnatural direction, while it preserves, at the same time, a remarkable symmetry of the whole structure.

The following outline of one of these skulls, will further illustrate my meaning; merely premising that the course of the bandages is in every instance distinctly marked by a corresponding cavity of the bony structure, ex

cepting on the forehead, where the action of a firm compress has left a plane surface.

This conformation, as we have already observed, was prevalent among the old Aymara tribes which inhabited the shores and islands of the Lake of Titicaca, and whose civilization seems evidently to antedate that of the Inca Peruvians. I was in fact at one time led to consider this form of head as peculiar to, and characteristic of, the former people; but Mr. Foster's extensive observations conclusively prove that it was as common among some tribes of the sea coast, as among those of the mountainous region of Bolivia; that it belonged to no particular nation or tribe; and that it was, in every instance, the result of mechanical compression.

In my Crania Americana I have given abundant instances of a remarkable vertical flattening of the occiput, and irregularity of its sides, among the Inca Peruvians who were buried in the royal cemetery of Pachacamac, near Lima. These heads present no other deviation from the natural form; and even this irregularity I have thought might be accounted for by a careless mode of binding the infant to the simple board, which, among many Indian tribes of both North and South America, is a customary substitute for a cradle. It is probable, however, that even this configuration was intentional, and may have formed a distinctive badge of some particular caste of these singular people, among whom a perfectly natural cranium was of extremely rare oc

currence.

We are now acquainted with four forms of the head among the old Peruvians which were produced by artificial means, viz: 1. The horizontally elongated, or cylindrical form, above described.

2. The conical or sugar-loaf form, represented in the preceding diagrams.

3. The simple flattening or depression of the forehead, causing the rest of the head to expand, both posteriorly and laterally; a practice yet prevalent among the Chenooks and other tribes at the north of the Columbia river, in Oregon.

4. A simple vertical elevation of the occiput, giving the head in most instances a squared and inequilateral form.

A curious decree of the ecclesiastical court of Lima, dated A. D. 1585, and quoted by the late Prof. Blumenbach, alludes to at least four artificial conformations of the head, even then common among the Peruvians, and forbids the practice of them under certain specified penalities. These forms were called in the language of the natives, "Caito, Oma, Opalla, &c. ;" and the continuance of them at that period, affords another instance of the tenacity with which the Peruvians clung to the usages of their forefathers.

SECOND SERIES, Vol. II, No. 1.-July, 1846.

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ART. II.-On a new process for obtaining Formic Acid, and on the preparation of Aldehyde and Acetic Acid by the use of the Bichromate of Potassa; by Profs. W. B. ROGERS and R. E. ROGERS of the University of Virginia.

I. Process for Formic Acid.

SINCE the important discovery of Döbereiner, that formic acid. is evolved from a mixture of tartaric acid, peroxide of manganese and sulphuric acid, the progress of research has shown that in a large proportion of cases, where organic matters are exposed to powerful oxidating agencies, this acid is among the products developed; and hence several other processes have been devised for its preparation, on the large scale and in the laboratory. Of these the one generally in use consists, as is well known, in distilling a mixture in prescribed proportions, of peroxide of manganese, dilute sulphuric acid and starch or sugar.

The inconsiderable amount of acid yielded by this process, and its usually large admixture with other products, especially sulphurous acid, suggested to us, some time ago, the trial of bichromate of potassa, as a substitute for peroxide of manganese, and has since led us to a method of operating, which we think presents decided advantages over that in general use.

When bichromate of potassa, dilute sulphuric acid and sugar are mingled in proper proportions and in a proper order, a large amount of formic acid is developed, of which part passes off during the first violent reaction, and the remainder is separable by gentle distillation. Repeated experiments have convinced us that by mingling all the materials at once, before placing them in the retort, a comparatively small product is obtained, partly from its being volatalized by the high temperature attending the reaction, and partly, we think, because more of the sugar is carried to its highest stage of oxidation in the forms of carbonic acid and water. We have therefore been led to another, and we believe, better mode of operating, of which the following details will serve as an example.

Introducing into a retort, capable of holding about one quart, 800 grains of bichromate of potassa and 10 cubic inches of water, we gently heat the mixture so as to dissolve the larger part of the bichromate. We then add 300 grains of powdered white sugar,

and adjusting to the tubulure a perforated cork and pipette with gum-elastic bag for the gradual introduction of sulphuric acid, we slowly inject about 1 cubic inch of the latter upon the mixture. By regulating the addition of the acid and occasionally intermitting the slender stream, the violent reaction which ensues is prevented from occasioning any very great intumescence. During this stage of the operation, upwards of 2 cubic inches of a clear but feebly acid liquid passes over into the receiver. When the action has in a good measure subsided, we add 5 cubic inches more of water, and apply a gentle lamp heat, continuing the addition of the acid, by allowing it simply to drop from the pipette, until another cubic inch has been introduced. The liquid which now passes over is much stronger in formic acid than in the preceding stage, and the distillation may, without impairing the purity of the product, be continued until about 7 cubic inches have been received. By urging it much beyond this point sulphurous acid will be evolved.

One hundred grains of the liquid thus obtained is capable of saturating about seven grains of dry carbonate of soda. Its purity is such as to fit it for immediate use in illustrating the striking reactions of formic acid and the formiates. Thus

1. On adding a small portion of it to a solution of nitrate of silver previously curdled by ammonia, and applying heat, the silver is promptly reduced with a lively effervescence of carbonic acid.

2. With a solution of bichloride of mercury, aided by heat, it causes a precipitation of calomel and the evolution of hydrochloric and carbonic acids.

3. Combined with soda it forms a white salt readily carbonized by heat and passing into carbonate.

4. It is not blackened by sulphuric acid, but the soda salt acted upon by this acid evolves carbonic oxide with brisk effervescence. 5. This salt heated with solution of nitrate of silver or nitrate of mercury, precipitates the metal with evolution of carbonic acid.

All these results are so prompt and striking as to evince but little contamination of the formic acid with other products.

On comparing this process with that commonly employed, we are convinced of its superiority, first, on account of the exemption of the product from SO,, and in a great degree from other

impurities; second, from the much larger amount of formic acid obtained by it from an equal weight of the oxidizing material, sulphuric acid and starch or sugar; and third, from the ease with which the action is controlled.

According to Liebig, (Chem. Org., p. 567,) 10 parts of starch, 37 parts of peroxide of manganese, and 30 parts of sulphuric acid, yield 3-35 parts of an acid liquid, of which 100 grains saturate 15 grains of carbonate of soda. This corresponds to 7.18 parts of liquid such as we obtain. We have thus by the old process 7.18 parts of liquid of equal acidity with our product, while the aggregate weight of the starch, sulphuric acid, and peroxide of manganese is 77. By our process we have about 1800 grains of a similar acid from 2100 grains of sugar, bichromate of potassa and sulphuric acid. In other words, by the new process, we procure about nine times as much formic acid from the same weight of the three reacting materials, as by that hitherto in use.

II. On the preparation of Aldehyde and Acetic Acid by the use of the Bichromate of Potassa.

In the process described by Liebig, (Chem. Org., p. 378,) and which is the one hitherto generally used for preparing aldehyde in the regular way, the product is obtained from the reaction of peroxide of manganese and sulphuric acid upon dilute alcohol. This operation furnishes a liquid which is so weak in aldehyde, and so mixed with water and formic ethers, and as we have found with acetic acid also, as to present the characteristic reactions only in a feeble degree, and to require two rectifications over chloride of calcium, before it can be used in forming the subacetylite or aldehydite of ammonia.

In the course of some experiments upon the reactions of bichromate of potassa and sulphuric acid upon alcohol, we have been led to a process which affords a larger and much purer product, and which is entirely under the control of the operator. The distinctive features of this method are the substitution of bichromate of potassa for the peroxide of manganese, and the peculiar mode of bringing the reacting materials together. In the use of the bichromate we have since found that we were anticipated by Prof. Kane, who, at page 922 of his Elements of Chemistry, recommends it as a means of obtaining a purer pro

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