Inferences from the foregoing Experiments.

It may be inferred from the foregoing experiments, that an important adhesion of brickwork had taken place by the use of Pozzolano, sand and lime, in the short period of thirty days.

That from the use of Pozzolano and lime in the proportions specified, almost all the advantages required from a good building cement were obtained.

That Lord Mulgrave's or Atkinson's cement had, in the short period of twenty-three days produced an induration which was sufficient to maintain almost any weight brickwork was capable of for openings in buildings; the effect probably would have been the same in Parker's, had the material not set before the bricks were fixed in it, further, that Pozzolano had not, in that period, produced an equal adhesion, and that common mortar had produced hardly any; and it appears from the splitting of the large piers thrown down on the 21st April, that an increasing induration took place; this was evident from the nearly equal fracture of the bricks and cement.

The incompressibility of mortar being one of its most material qualities, it results that Parker's, Mulgrave's, and Pozzolano, are so far equally useful, that brickwork composed with them will bear on each superficial foot before the bricks will crack, about twentythree tons, that fifty tons will totally crush such brickwork; and that Portland stone, of the best quality, will not split with less than one hundred seventy-three and a half tons, and that a bedding or joint of Pozzolano mortar is not destructible with that weight.

ART. IX. Remarks on Phytolacca Dodecandra, or, the Mustard Tree of the Scriptures. By John Frost, F.L.S., Member of the Royal Institution, &c.

[Communicated by the Author.]

THE remark in the sacred volume, that a grain of mustard seed should become a tree, must have appeared to many very pa

* Luke, chap. 13, ver. 19, "A grain of mustard seed which a man took and cast into his garden: and it grew and waxed a great tree, and the fowls of the air lodged in the branches of it."

It

58 Mr. Frost on the Mustard Tree of the Scriptures.

radoxical; for what we know under that name is procured from an annual plant, (sinapis nigra of Linnæus,) which has an herbaceous stem, and never attains a greater height than three feet; therefore it is quite evident that that cannot be the plant referred to, the word ddpor, which is used, implying a shrub, or tree, and of course not any plant like sinapis nigra, with an herbaceous stem. I am not acquainted with any species of sinapis that can be called a shrub, much less a tree.

The author of a Theological Dictionary, of some repute at the present day, has stated under the article mustard seed, that the mustard tree alluded to by our Saviour was a species of sinapis, and asserts as a proof of the correctness of his definition, the fruit of all the members of that genus having a cruciform corolla.

The plant most likely to be the mustard tree of the Scriptures is a species of Phytolacca", which grows abundantly in Palestine; it has the smallest seed of any tree in that country, and attains as great an altitude as any. This circumstance, together with that of its being indigenous to the place where the observation was made, are sufficient to convince us of the identity of the tree referred to. In addition to which I can adduce two facts which will greatly tend to confirm this opinion.

The first is, that of the Americans using the fresh sliced root of Phytolacca Decandra† for the same purpose as we use mustard seed, viz., that of a Cataplasm. I have been informed that they call it (P. decandra,) wild mustard.

The second is, that of the seed of a species of Phytolacca affording what the seed of sinapis nigra does in great abundance, nitrogen; an element not found in many plants, excepting those which belong to the natural orders Cruciatæ and Fungi. These

It may here be proper to state that the term waTIOS σιναπι in the original language of the New Testament, does not signify the seed which is obtained from any species of the genus which we know by the term Sinapis.

* Phytolacca, derived from purov, a plant, and lacca, or lac, a gum resi nous exudation, of a red colour. The petioles of every species of Phytolacca, which I have seen, have a degree of redness, more or less.

This is a perennial herbaceous plant, a native of Virginia, occasionally found in our gardens under the name of the American Soke-Weed.

Mr. Frost on the Mustard Tree of the Scriptures. 95

two facts prove the analogy between the properties of the genera Phytolacca and Sinapis. Linnaeus, in his Materia Medica, points this out very clearly.

It appears that the mustard tree of the Scriptures is undoubtedly a species of Phytolacca, most probably P. dodecandra of Linnæus. I cannot be quite positive as to the species, as the plant which is the subject of this communication has not yet flowered.

29th August, 1825.

Observations on an Emetic Oil termed "Pinhoën Oil."

AN expressed oil has just been sent to me from the Brazils, under the name of Pinhoën oil. It is used there as an emetic, and acts powerfully in the small dose of one or two drops.

It appears to be procured from the seed of a species of Jatropha, of which there are several indigenous to South America, most likely J. multifida, the fruit of which has been long known under the appellation of the French Physic-Nut. From some experiments which I made about two years since on the seeds of several species of Jatropha, I am inclined to think that there can be but little doubt of the plant which yields this emetic oil being of the genus just mentioned. And it may here be remarked, that the expressed oil of the seed of very many species all produce emetic and cathartic effects; the former attended by a sensation of heat about the fauces, and by doubling the dose, drastic purgative effects ensue.

Mr. Reeves, of Canton, informed me that the varnish which the Chinese are so famous for making for covering paper boxes, tea chests, &c., is formed by boiling the expressed oil of the seeds of Jatropha curcas, with oxide of iron. The seeds of J. curcas have frequently been mistaken for those of Croton tiglium, only, one can suppose, from there being a degree of analogy between their effects, as there is none in point of appearance.

ART. X. A Monograph of the Genus TACHYPHONUS; a group of Birds belonging to the Tanagra of Linnæus. By William Swainson, Esq., F.R. and L.S., &c.

[Communicated by the Author.]

THE new objects in the higher departments of zoology continually coming before us, have, on many occasions, confirmed the justness of those views which have led to the formation of new divisions. Several of the genera, proposed but a few years ago by the continental ornithologists, and which were then supposed to rest on the authority of a solitary example, have since been augmented by a host of others, hitherto unknown to naturalists, or indiscriminately scattered in different genera of the Linnæan system.

On the other hand, several of these groups, either from not having attracted particular attention, or from no new examples having been brought to light, remain confined within their original limits.

M. Vieillot has given the generic name of Tachyphonus to the fifth division of the Linnæan Tanagers, as arranged by that acute ornithologist M. Desmarest, and in which is comprised only two species, the Tanagra nigerrima of Gmelin, and the Tanagra cristata of Linnæus; both natives of South America. During my residence in Brazil, I was fortunate in procuring several other species, evidently belonging to this group, and which seem to be hitherto unrecorded. This latter point, however, is doubtful; for within the last few years the provinces of Brazil have been traversed in almost every direction, by many learned and indefatigable naturalists, who are now occupied, under the patronage, and even at the expense of the continental governments, in publishing ample and richly illustrated accounts of their extensive discoveries in every branch of natural science. Under these circumstances we must receive all descriptions of the productions of Brazil, so far as their novelty is concerned, with a certain degree of doubt. In the absence of an extensive and public zoologicallibrary, few of these costly works are accessible, and the treasures collected in many of them do not appear till after an interval com

mensurate with the care and expense employed to render them worthy of their immediate patrons. If this be well understood, I see no reason why we should withhold the contribution of our mite towards the general stock of knowledge, under the apprehension of doing that imperfectly, which others may have previously done well; and with the possibility that, after all, the materials for such a contribution may rest alone with ourselves.

I am unprepared to offer any detailed remarks on the situation which Tachyphonus may be supposed to occupy among the Tanagræ. By its strong, conic, and somewhat lengthened bill, and by the sinuosity of the margin of the upper mandible, this group seems to have a close affinity with Pyranga. Some species in which the bill is much shorter and proportionably thicker, might, at first sight, be mistaken for Fringille; while in others †, the form of this organ is considerably modified, and resembles that of Tanagra velia, and its allies. But the typical species are more particularly distinguished by the elevated base of the bill, which is carried on towards the crown, and divides the frontal feathers. This character, so much developed among the Icteri of the new world, and, in a less degree, among the African weavers, probably induced the writers of the last century to associate the type of this group with the Linnæan Orioles.

We have little or no information respecting the manners or economy of these birds; judging from the hardness and general strength of the bill, the margins of which are frequently inflexed, we may suppose that they feed principally upon seeds; but, in some species §, the base of this organ is widened, and the bristles of the rictus are sufficiently lengthened to indicate a partially insectivorous disposition.

The colour of the plumage is frequently an obvious, though not an essential, character in natural groups. In Tachyphonus it is usually black, or of one uniform tint on the upper parts, unbroken by spots, and unrelieved by those beautiful colours which so ornament many of the Linnæan Tanagers. Nevertheless the head

* Tachyphonus rubescens. T. fringilloides. T. Desmaresti. T. tenuirostris. T. nigerrimus. T. olivaceus. T. Vigorsi. § T. Suchi. T. cristatus.?