at the commencement of the gouty attack, no uric acid could be detected in it, although on the third day a trace could be discovered by the murexide test, and a few crystals were deposited, whilst the blood during this time gave abundant evidence of its presence. When the attack had subsided, the uric acid was present in the urine in its normal quantity.

In the urine of the patient (II.) when the attack was passing off, the uric acid amounted to 0.050 gr. only; hence not more than one-twelfth of the natural quantity. The same fact was proved to occur in other cases.

usually exceeds that found in ordinary blood.
Urea always exists in large quantities in this
blood, as is well known, and no relation is
found between the amounts of urea and uric
acid. In the examination of the blood in
albuminuria, some of the coloring matter of
the urine seemed to be thrown down with
the uric acid in all cases. The author re-
gards the quantities of uric acid found by
him in the blood in his earlier experiments
as rather below the true amounts.
recommends that the crystals should not be
collected until forty-eight hours have elapsed.

He

The author suggests whether, in doubtful cases, it might not be possible to determine as to the presence of gout or rheumatism from an examination of the blood.

3. In patients subject to chronic gout with topacheous deposits, the uric acid is always present in the blood and deficient in the urine, both absolutely and relatively to the other organic matters; and the chalk- ON SEA-WEEDS AS THE SOURCES like deposits appear to depend on an action in and around the joints, &c., vicarious of the "uric-acid-excreting" function of the kidneys.

4. The blood in gout sometimes yields a small portion of urea (no albumen being present in the urine), as shown by the crystallisation with nitric acid.

OF ACETIC ACID.

BY JOHN STENHOUSE, LL.D., F.R.S. L.
AND E.

DURING the course of a series of experiments on sea-weeds, an account of which was read before the Royal Society on the 18th of April, 1850, I had frequently occaThe quantity of uric acid in the blood of sion to observe that when a quantity of wet healthy persons, or at least those suffering sea-weeds was laid together in a heap in a from slight headache or other trifling affec- warm situation for any length of time, it tions, was found to amount, per 1000 grs. soon began to undergo a species of fermenof serum, in one case to 0·007 gr., in ano- tation. This, I am aware, is a circumstance ther to a trace only; in two patients suffer- which has been not unfrequently observed; ing from slight paralysis and an ill-condi- but as no one has hitherto been at the tioned habit of body, to 0.010 gr. No trouble to examine the nature of the acids trace could be found in the blood of the generated during this fermentation, I was sheep nor in that of the pigeon; the urine induced to investigate the matter a little of the former contains no uric acid, whilst more closely. that of the latter consists entirely of urate of ammonia.

The author moreover found, in several examinations of perfectly healthy blood, that uric acid was invariably present.

It appears, then, from these experiments, that in health (or tolerable health) uric acid can be detected in the blood of the human subject. It appears also, that when the function of excretion is very perfectly performed, no trace can be detected, although, as in the case with birds, the amount of uric acid formed in the system is very large.

In regard to rheumatism, the author found the blood to contain no more uric acid than in health; and no urea could be detected in 1000 grs. of serum.

In cases of albuminuria, uric acid is always present in the blood; the quantity however varying. When the functions of the kidneys are much impaired, it exists in quantities almost as great as in gout; in other cases its amount is small, but it

At the ordinary temperature of Scotland, even during the summer months, the fermentation of sea-weeds proceeds very slowly, requiring from three to four months for its completion; but when the weeds are kept at a temperature of from 90° to 96° F. the process is completed in from two to three weeks.

I. Six pounds of fresh moist Fucus vesiculosus were put into an earthenware jar along with a little quicklime, and just sufficient water to cover them, and were kept for three weeks at the temperature of 96° F. Small quantities of quicklime were added from time to time, so as to keep the mixture slightly alkaline. When the fermentation was completed, the liquid portion, which contained a good deal of mucilage and some acetate of ammonia, was thrown upon a cloth filter, and the clear liquid which passed through was evaporated to dryness and then cautiously heated, so as not to decompose any of the crude acetate of lime, while

H

portions of Europe, at least during the summer months, and in tropical countries, artificial heat might probably be dispensed with.

almost the whole of the mucilaginous was | should expect, however, that in the southern rendered insoluble. The dark brown mass was digested with a little water, again filtered, and the clear solution evaporated to dryness. It yielded 4 oz. 2 drams of dry acetate of lime, which was almost entirely One of the chief uses to which sea-weeds free from adhering organic matter. When are applied is in manuring land; and with this acetate of lime was distilled with hydro- this application, their having been previchloric acid, it yielded 29 oz. of a pure but ously employed in the manufacture of feeble vinegar, 1 oz. of which required 24 vinegar would not very materially interfere; grs. anhydrous carbonate of soda to neu- for if the fermented weeds and the salts tralise it. As, therefore 662 grs. of anhy-remaining in the still were spread upon the drous carbonate of soda require for satura-land, I apprehend they would prove almost tion 650 grs. of anhydrous acetic acid, 1 as useful in an agricultural point of view as grain of anhydrous carbonate of soda may the fresh sea-weeds would have done. be regarded as equivalent to 1 gr. of anhydrous acetic acid. The 29 oz. of the abovementioned vinegar, therefore, contained 24 × 1 × 29=696 grs. of anhydrous acetic acid. As 1 pound contains 7000 grs., and 6 pounds of fucus consequently 42,000 grs., the 696 grs. of anhydrous acetic acid obtained from it give 1.65 per cent. anhydrous acetic acid as the produce of the wet seaweed.

II. Twenty-four pounds of fresh Fucus nodosus, also in a moist state, were suffered to ferment along with lime at a temperature of 96° F. for about five weeks. Twenty ounces of crude acetate of lime were obtained, which, when distilled with hydrochloric acid, yielded 57 oz. of pretty pure vinegar, each ounce of which saturated 43 grs. of anhydrous carbonate of soda. The amount of the acetic acid in the whole quantity was therefore 2451 grs.=1.45 per cent. of the wet Fucus nodosus.

III. Four pounds of fresh Fucus vesiculosus were left to ferment in the open air along with quicklime, at the ordinary temperature, from the 8th of June to the 1st of September, when the process was finished. The filtered solution of the acetate of lime, after being evaporated to dryness, when distilled with hydrochloric acid, yielded 46 oz. of weak vinegar, each ounce of which saturated 7 grains of anhydrous carbonate of soda, amounting therefore in all to 322 grs. of anhydrous acetic acid=1.15 per cent. of the wet sea-weed. Thus it is clear that when sea-weeds are fermented at the ordinary temperature of Scotland, during the summer months the process goes on much more slowly, and yields a considerably smaller product than when the temperature is retained at about 90° F. Should any person, therefore, think of manufacturing acetic acid from sea-weeds, either in Great Britain or in any of the northern countries of Europe, I would advise him to employ so much artificial heat as to produce a constant temperature of from 90° to 96° F. 1

The vinegar obtained from the Fuci contained a very minute quantity of butyric acid. When it was therefore saturated with carbonate of soda, evaporated to dryness, and the dry salt left for some time in a moist atmosphere, a small portion of it deliquesced. This liquid portion was therefore separated from the solid salt, and was evaporated to dryness. It formed a saponaceous-looking, uncrystallisable mass, which had the peculiar odor of the butyrates; and when it was digested in a mixture of alcohol and sulphuric acid yielded an ether which had the characteristic odor and properties of butyric ether. A silver salt, prepared from this supposed butyrate of soda by double decomposition with nitrate of silver, was found to contain 60.49 per cent. oxide of silver. The calculated quantity of oxide of silver in butyrate of silver, is 59-48; that in acetate of silver, 69-46; and in metacetonate of silver, 64-00 per cent. It appears highly probable, therefore, that the excess of oxide of silver found in the butyrate arose from a slight admixture of either acetic or metacetonic acids.

A silver salt was also prepared by digesting oxide of silver with pure acetic acid from the Fuci. It had all the characters of acetate of silver; and when subjected to analysis, 0.250 of the salt gave 0.161 metallic silver=0·172 oxide of silver=69.16 per cent.; the calculated amount of oxide of silver in the acetate being, as was previously stated, 69-46 per cent.

Glasgow, Nov. 26th, 1850.

ON GITHAGIN.*

BY DR. E. A. SCHARLING.

DR. SCHARLING has extracted from corncockle (Agrostemma githago) a peculiar

Central Blatt and Pharmaceutical

Journal.

poisonous principle, to which he has given the name of githagin.

The seeds of corncockle contain githagin, fatty oil, gluten, sugar, gum, starch, vegetable albumen, and the usual salts of the vegetable kingdom.

Githagin, when dry, resembles starch, but has a more silky appearance, and under the microscope appears somewhat crytalline. It is odorless and almost tasteless: after a short time a burning sensation is felt on the palate. It does not act on vegetable colors. It is soluble in water and dilute spirit, but is insoluble in absolute alcohol and in ether. It is reddened by sulphuric acid like salicine. Its aqueous solution yields a precipitate with subacetate of lead.

Githagin acts as a poison on the smaller animals. A few drops of a solution (three grains of githagin in a drachm of water) killed a canary bird in twenty-four hours. A solution of ten grains killed a rabbit. Ten grains of githagin merely caused vomiting in a dog.

ON POTASSIO-GYPSITE, A DOUBLE
SULPHATE OF POTASSA AND LIME.

BY J. ARTHUR PHILLIPS, ESQ.
THIS substance is obtained as a secondary
product in the manufacture of tartaric acid,
and it will therefore be necessary to describe
the circumstances under which it is pro-
duced, before detailing the properties and
composition of the salt itself. Tartaric acid
is, as is well known, made from the impure
bitartrate of potassa, which reaches this
country in such a state as to yield, on an
average, 72 per cent. of crystallised acid.

The processes employed in the manufacture are briefly as follows: Into a large tun, capable of containing about three thousand gallons of water, are thrown from fourteen to fifteen hundred pounds of mashed chalk, which is agitated by means of a revolving arm, until the water and carbonate of lime have become perfectly incorporated, and a finely-divided mixture is obtained. When this is effected, about two tons of crude tartar are added, by means of an air-tight trap on the top of the vessel, and by the aid of heat, obtained by blowing a jet of steam into the mixture, and constant agitation of the mass, the bitartrate of potassa is made to transfer its free atom of acid to the lime, giving rise to insoluble tartrate of lime, soluble tartrate of potassa, and the evolution of carbonic acid, which is conveyed

away in leaden pipes to be employed in making bicarbonate of soda. As soon as the decomposition is completed, a sufficient portion of sulphate of lime, from a preceding operation, is added, for the purpose of decomposing the neutral tartrate of potassa in solution. By the aid of heat and longcontinued agitation, this is at length effected, and the vessel then contains a solution of sulphate of potassa, together with the insoluble tartrate of lime, and small portions of the carbonate and sulphate of the same base, arising from the excess of these reagents originally employed. At this period of the manufacture, the agitation is arrested, the liquor is allowed to settle down, and the sulphate of potassa drawn off from the tartrate of lime, which remains at the bottom of the tub. This is subsequently washed with three successive waters, which are added to the solution of sulphate of potassa at first obtained. The insoluble tartrate of lime is afterwards decomposed by sulphuric acid, with formation of sulphate of lime and production of free tartaric acid, which is crystallised in the usual way, whilst the sulphate of potassa, with which we are at present most interested, is conveyed away by large leaden gutters for evaporation.

At the manufactory of the Messrs. Pontifex, these liquors are first drawn into a large tubular steam-boiler, heated by the waste heat escaping from a set of cokeovens. In this the potassa solution is concentrated to about two-thirds of its original volume, and then allowed to run into a series of large bacs containing coils of iron pipe, which are supplied with steam by means of the boiler in which the liquor is concentrated, and in these the evaporation is completed.

This boiler for concentration and supplying the steam-coils, gradually becomes coated by a hard deposit, in order to remove which, it becomes necessary, at intervals of about three months, to stop the ovens and run out the liquor. On these occasions, the cooling of the boiler and its contents is extremely slow, as the mass of brickwork which surrounds it renders the loss by radiation very inconsiderable. When it has sufficiently cooled, and the liquor has been run off, the greater part of its internal surface is found to be covered with transparent lamellar crystals, formed on a hard crystalline gangue. These are sparingly soluble in water, but are easily dissolved by dilute hydrochloric acid.

A qualitative analysis showed them to consist of lime, potassa, water, and sulphuric Quarterly Journal of the Chemical acid, and a quantitative examination gave Society, January, 1851. the following results :

from the oxalate of lime was then evaporated to dryness, and the residue heated to redness to expel the ammoniacal salts. A slight excess of hydrochloric acid was afterwards added, and the potassa estimated as platino-chloride of potassium.

In the investigation of the uncrystallised deposit, the ordinary routine of chemical analysis was employed, the phosphoric acid being estimated by the method of Fresenius, and the alkalis separated from the alkaline earths by the use of hydrate of baryta.

ON A METHOD OF DETERMINING
THE EFFECTIVE HARDNESS OF
EMERY, WITH OBSERVATIONS ON
ITS CHEMICAL COMPOSITION.*

BY J. LAWRENCE SMITH.

FRAGMENTS are broken from the piece to be examined, and crushed in a diamond mortar with two or three blows of a hammer, then thrown into a sieve (the one employed had four hundred holes to the square centimetre), the portion passing through is collected, and that remaining on the sieve is again placed in the mortar and two or three blows given, then thrown into the sieve; the operation is repeated until all the emery has passed through the sieve. The object of giving but two or three blows at a time is to avoid crushing any of the emery to too fine a powder.

Thus pulverised, it is intimately mixed, and a certain portion of it is weighed (as I operated with a balance sensible to a milligramme, the quantity used never exceeded a gramme). To test the effective hardness of this, a circular piece of glass about 4 inches in diameter and a small agate mortar are used. The glass is first weighed, and placed on a piece of glazed paper; the pulverised emery is then thrown on it little by little, at each time rubbing it against the glass with the bottom of the agate mortar.

The emery is brushed off the glass from time to time with a feather, and when all the emery has been made to pass once over the glass, it is collected from the paper and made to pass through the same operation, which is repeated three or four times. The glass is then weighed, after which it is subjected to the same operation as before, the emery being by this time reduced to an impalpable powder. This series of operations is continued until by repeated weighing the loss sustained by the glass is reduced to a few milligrammes. The total loss in the glass is then noted; and when all the specimens

* Silliman's Journal, November, 1850.

of emery are submitted to this operation under the same circumstances, we get an exact idea of their relative hardness.

The blue sapphire of Ceylon was pulverised and experimented with in this way; it furnished me with a unit of comparison by which to compare the results obtained. This operation is long but certain, and for the harder varieties of emery it is necessary to repeat the rubbing six or seven times, and it requires nearly two hours for completion.

The results that I have obtained are interesting, and have furnished me with the means of forming conclusions that I could not otherwise have come at.

Glass and agate have not been chosen for this experiment without a certain object, as experiments were first made with two pieces of agate, with two pieces of glass, and with metal and glass. The agates were found too hard, as they crushed the emery without producing hardly any abrasive effect; the others were found not to crush the emery sufficiently, making the experiment tedious and long. With the glass and agate we have a hard substance which crushes the emery, and in a certain space of time reduces it to such an impalpable state that it has no longer any sensible effect on the glass, and on the other hand the glass is soft enough to lose during this time sufficient of its substance to allow of accurate comparative results. In the employment of this method in the arts, it wonld not be necessary to go to the sapphire for a standard of comparison; any good emery would answer the purpose quite as well.

It must be understood that this method of coming at the abrasive effects of emery does not furnish the mineralogical hardness of this substance, by which we understand the hardness of any individual particle, as evinced by its effect on a substance of less hardness, without regard to the molecular structure of the mineral. Two minerals possessing the same hardness, but differing in structure, one being friable and the other resisting, will be found very different in their abrasive effects: for instance, break a piece of quartz in two; subject one of the pieces to a white heat, and after cooling compare the two by rubbing the point against some hard substance; both will be found to scratch equally well. Then try the two in a state of powder, by rubbing them between two pieces of glass that have been weighed, and the difference of their abrasive effects will be found very great, because the one subjected to the fire is exceedingly friable, and becomes readily crushed to an impalpable powder. This fact is eminently