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Samuel Preston of Stockport, Wayne county, Pennsylvania, first observed it about six years ago.*-At first it was ascribed to the Gypsum, which was strewed early in the spring on the clover; but this theory cannot be correct, because second crops of other kinds of grass will salivate equally with clover, although they never were plastered. This I have had full opportunity of knowing, and the fact is agreeable to the observations of several others whom I have questioned as to the point. Timothy grass will have the effect, but not to the extent of clover; even green grass in some years is not free from the bad quality. It was also supposed to be confined to second crop red clover, but the fact just mentioned, with that stated by Thomas Moore, viz. that the disease was unknown in certain parts of Pennsylvania, where red clover' had been much longer in use than in his neighbourhood, fully refute this opinion. On the other hand, Mr. Preston says, he has observed the disease to travel with the cultivation of clover, but this only proves that the disease is in some way connected with the cultivation of that plant. Mr. Preston remarks, that white frost puts a stop to the complaint, and hence he concludes that frost kills some plant which he supposes is the cause of the disease. It prevails in some seasons with much more violence than in others: last summer was remarkably cold and wet, and his horses had the disorder worse than ever: it not only re. duced their flesh, strength and spirits, but rendered them incapable of service; they were therefore stabled and fed on dry hay. One young horse was neglected by not being put up, and died from the effects of the salivation. In a former letter however, he remarks, that "he knows of no change in the quality of his pasture during the time the disease continued," neither, says he, “do I know how to impute it altogether to the wet seasons, as we have had more or less of it for several seasons." This fact is conformable to my own experience, and that of others whom I have consulted.

In a communication on this subject by Dr. Perlee, of Wilming

Letter to the Author.

ton, Delaware, to the Agricultural Society of Philadelphia,* the disease is ascribed to the spotted spurge, the Euphorbia maculata of Linnæus, which grows with the clover, and flowers, about the same time as the second crop of clover.

He gave a horse a small quantity of spurge carefully gathered stem by stem, and perfectly free from all other vegetables, or any extraneous matter. A preternatural discharge of saliva took place in less than half an hour. This experiment was frequently repeated, and invariably with the same result. To prove that clo ver did not contribute towards it, in some cases, other grass was used as an envelope with the same effect. And when the horse was perfectly free from ptyalism, a considerable quantity of clover, gathered without Euphorbia, was given to him, and no such effect was produced. But this does not prove that the spurge is alone in fault, for Thomas Moore found that clover carefully picked produced the same effect: and a botanical friend who knows Euphorbia well, assures me he examined a field belonging to himself with great accuracy, without finding a plant of that genus in it, and yet a horse in the field, was slabbering profusely.

On a recent discussion of the subject at the Agricultural Society, a member mentioned, that a labourer, who in stacking a second crop of clover, had his arms, which were bare, covered with very small insects from the hay, said that they were the cause of the salivation in horses. He ascribed the effect to the acidity of the insect. Thomas Moore's fact of the change produced on a purple cloth by the saliva of a horse, supports the opinion.

There is certainly something very disagreeable to cattle in second crop clover hay. They do not relish it, and even in some cases refuse it. Mr. John Lorain of Philadelphia county, bought some cattle in the autumn of 1809, and found that after his corn stalks and stubble hay had been consumed, they in general refused second crop clover, although it had been well got in, and salted: a few eat it sparingly, and after some time they fell away in esh, and in 21 days, during which time he tried to induce them

* See Memoirs Agricultural Society, Philad. Vol. 2.

to eat the clover, they began to scour, and were worth $200 less than when they began on it. He then mixed equal parts of green grass hay (Poa Viridis) and second crop clover, and found that they eat it more readily, but that they still did not relish the mixture. Mr. Lorain had previously given to the cattle corn fodder, but discovered that it was strongly disliked at first even by those which had eaten it readily the year before, as well as by the new cattle, and that they preferred the old thatch on the sheds, and dry leaves in the barn yard, until they had been fed on about one acre of fodder, from corn planted in July for boiling or roasting ears; which being very succulent was eaten greedily, and after it was all consumed, they showed no dislike to the other.

Method of preventing the Accidents which frequently happen from the Linch Pins of Carriages breaking or coming out, by Mr. J. Varty, coachmaker, Liverpool. From the Transactions of the Society for the Encour The Silver Medal was agement of Arts, Manufactures, and Commerce. voted to Mr. Varty for this Invention.

HEREWITH the Society will receive a model of an axletree for public machines, intended to prevent the wheel from coming off if the linch-pin should break, and thereby prevent many dangerous consequences. When the idea first suggested itself to me, I put it in practice in a stage-coach, which has since run from Liverpool to Litchfield, a distance of eighty-four miles, six days per week, for the last six months. During that time several instances have occurred in which the linch-pins have broke or come out, but owing to this contrivance no accident has happened therefrom. We almost daily hear of stage-coaches being upset, which more frequently arises from linch-pins breaking than from any other cause.

This faot cannot be accounted for: as it is well known, that cattle are commonly very fond of corn fodder-Editor.

Certificates were received from Liverpool from several persons, who declared that they have witnessed many very melancholy accidents happening to passengers in stage-coaches, in consequence of the linch-pin breaking made in the common way, and from which some of them have been sufferers; but that they have never seen or heard of any such accidents where Mr. Varty's invention was made use of, though several of his linch-pins have broke.

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Fig. 1, is a section of the nave of a carriage wheel, with the axletree AA in it; and Fig. 2, is a separate view of the axletree. a, Fig. 2, is the linch-pin detached; it is put through an oblong hole in the axle as usual, but there is likewise an additional linch-pin b, to make it complete, which is fixed in a recess cut for it in the axle, and turns on a pin (as is shown in the figure) into the hole left, by removing the linch-pin a, when the wheel is to be taken off; but if the linch-pin a should accidentally get out, this additional pin 6 would effectually keep the wheel on, as its hanging position does not at all tend to shut the pin up into the axle, but the contrary. The common linch-pin a is put in downwards, that its weight may always tend to keep it in, and is secured in the usual way by a strap, the holes for which may be seen in the figures.

3 E

ON MANUFACTURING PYROLIGNEOUS ACID.

Acetate of Iron-or Iron Liquor, and Acetate of Alumine.

THE extensive use of these preparations by Dyers, and Calico printers, renders the knowledge of the mode of making Pyroligneous acid, of great importance; for this reason the following information is given. It is collected from various sources, but chiefly from the Commercial Magazine of London.

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THE name Pyroligneous has been given, because it was distilled from wood; it had been long known that the hardest woods afforded an acid principle mixed with an oil, which partly disguised its properties. But no one had directly attended to a determination of the habitudes of this acid, until Mr. Goettling published his researches on the acid of wood, and the ether it affords. The following is the most common method practised to obtain it.

Having a large cast iron cylinder, one end of which can be opened to admit wood, and formed to shut so as to exclude the air. The cylinder is placed in such a manner, that the fire is under it to heat it as much as possible. Oak, in pieces about a foot in length, is put into the cylinder, which is filled as full as possible, without being wedged, and the door shut close to exclude air; from the cylinder is a worm that runs through cold water to condense the acid, by this it is conveyed to a large cask placed on one end, where there is a pipe to carry the acid from that to two or three more; thus the acid is completely secured from flying off in the vaporous state; the fire is raised to a great heat, sufficiently powerful to convert the wood completely into charcoal (coke.) When the acid is done coming over, the fire is taken out, and the mass is left to cool in the confined state, when it becomes perfect charcoal. is chiefly contained with the acid, it precipitates to the bottom, and is drawn off by a cock; it is afterwards boiled in an iron boiler to evaporate the acid before it is fit for use; if the acid is not strong enough, it is put into large square vats about

In the first cask tar

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