Professor Graham says (Elements, p 559), "of the 7 HO which copperas contains, it loses 6 HO at 238°, but retains 1 eq. even at 535°."

We have said that the Ferri sulphas exsiccatum of the Edinburgh Pharmacopoeia is not anhydrous, as represented by Dr. Christison; it is directed to be dried at "a moderate heat;" this is not defined in the present Pharmacopoeia, but in the former, calor lenis meant a temperature of between 90° and 110° of Fahrenheit, and we may perhaps consider the terms as synonymous, more especially as in preparing the Unguentum Citrinum the axunge is directed to be melted in the oil with the aid of a moderate heat;" now we have, as above quoted, Professor Graham's authority for stating that sulphate of iron retains one equivalent of water, even at 535°.

Dr. Thomson has made some observations on the action of dilute sulphuric acid upon iron in relation to this salt, which we confess we do not comprehend; he observes that, "the rapid decomposition of the diluted acid by the iron must be ascribed to the sum of the affinities of the base of the acid for oxygen, and of the iron for oxygen being superior to that of the oxygen to the hydrogen of the water, which is, therefore, decomposed." Now we do not comprehend how the affinity of sulphur, which is the base of the acid, for oxygen can play any part whatever in this operation.

Like Dr. Christison, Dr. Thomson has been very unfortunate in his statements respecting the water contained in sulphate of iron; he says, 'Mr. Phillips makes the proportions to be of acid 28.8, protoxide of iron 25.9, and water 45.3, or 1 eq. of acid =40.1+1 of protoxide of iron =36+6 eq. of water 54; making the equiv. of the salt 130-1 (Fe. S. +6 H.)" Now Mr. Phillips states distinctly that the salt contains 7 equivalents of water = 63, and he gives its formula FeO, SO3, 7HO, instead of that above represented by Dr. Thomson, who then goes on to say, “but, according to Prof. Graham, who regards one equivalent of the water to exist as a base, it contains only 5 eq. of water;" to this we will only add that the quotation which we have given from Prof. Graham, shews that this salt contains 7 equivalents of water.

Ferrum Tartarizatum.—It has been shown that Dr. Christison has very unceremoniously dismissed the Edinburgh College tests of the purity of Ferri Sulphas, and substituted his own for them; it will therefore excite no surprise that he should exercise the same discretion, or the same want of it, with regard to the tests of the London College; these are thus stated with regard to Ferri Potassio-tartras :-"In aquâ tota liquatur. Hic liquor lacmi et curcuma colorem non mutat. Nec a potassii ferrocyanido cæruleum fit; neque adjecto quovis alkali aut acido quicquid dejicitur. Magnes in ejus pulverem nullam vim exercet." The following is Dr. Christison's version of these statements: Entirely soluble: without action on litmus; unaffected by ferrocyanide of potassium, acids, or alkalis: not attracted by the magnet." The reader will observe that "in water" is omitted after "entirely soluble," solution before litmus, and turmeric after it; colorem non mutat, nec cæruleum fit, and neque quicquid dejicitur, are translated unaffected. It may indeed be admitted that the

"

meaning of the London College has in general been preserved, but to this there is one exception; the fact being that acids do affect this preparation, though, as correctly stated by the London College, they do not precipitate anything from it, yet they decompose it, for if hydrochloric or sulphuric acid be added to it, ferrocyanide of potassium, will then occasion the immediate formation of Prussian blue.

Dr. Christison remarks that chemists generally assume 80 as the true number for sesquioxide of iron, there are, however, exceptions to this, for Brande, Daniell, Henry, Murray, and Thomson give 40 as the equivalent of this oxide. Dr. Christison quotes Wackenroder to prove that Ferrum tartarizatum contains both protoxide and sesquioxide of iron, and that when it is decomposed by heating with potash, black oxide of iron is separated; this is certainly an error, not only in our experience, but as proved by Soubeiran and Capitain (Journ. de Pharm., 25, 138); partial deoxidizement of the sesquioxide occurs only when the heat applied to the preparation has been too great.

Dr. Thomson has in his worst manner made woful work with the London formula for this preparation; instead of three ounces of sesquioxide of iron as directed, he says twelve ounces and a half, for eleven ounces and a half of bitartrate of potash he mentions three, and three hours digestion are stated instead of two.

Corrosivus Sublimatus.-The tests of the Edinburgh College for ascer taining the purity of this preparation are, "it sublimes entirely by heat; and its powder is entirely and easily soluble in sulphuric ether;" but as we are informed by the same College with respect to camphor, that "its powder evaporates entirely when gently heated," and as Dr. Christison states, that "sulphuric ether is a good solvent of camphor," allow us to enquire wherein these substances differ?

Dr. Christison, in the Edinburgh process, has directed sulphuric acid, instead of commercial sulphuric acid, to be employed, and nitric acid instead of pure nitric acid; and Dr. Thomson has ordered half a fluidrachm of the last mentioned acid to be used in the place of half a fluidounce. He also states that this salt has an alkaline re-action, meaning we presume an acid one, for it reddens litmus paper and does not alter turmeric. With respect to the crystalline form of this salt Dr. Christison states that "it is a quadrangular prism terminated by two converging planes," while Dr. Thomson describes it as a "regular tetrahedron, compressed and pointed."

Unguentum Citrinum.-The following is the formula for preparing this ointment in both editions of the Edinburgh Pharmacopoeia :—

"UNGUENTUM CITRINUM.

Take of Pure Nitric acid, eight fluidounces and six fluidrachms;
Mercury, four ounces;

Axunge, fifteen ounces;

Olive-oil, thirty-two fluidounces.

Dissolve the mercury in the acid with the aid of a gentle heat. Melt the axunge in the oil with the aid of a moderate heat in a vessel capable of holding six times the quantity; and while the mixture is hot, add the solution of mercury, also hot,

and mix them thoroughly. If the mixture do not froth up, increase the heat a little till this take place. Keep this ointment in earthen-ware vessels, or in glass-vessels secluded from the light."

It has been discovered by Dr. Christison, as he states in a note p. 530 of his Dispensatory, that, "owing to an accidental error, the proportion of olive-oil has been stated in the Pharmacopoeia at 32 fluidounces, and the pure nitric acid of density 1500 has been ordered." The mistake here alluded to is afterwards explained by Dr. Christison to have arisen as follows: "An oversight has been committed in the College formula from an error made by Dr. Duncan. The proportions used by Messrs. Duncan and Flockhart are twelve ounces of nitric acid of the density 1380 to 1390, four ounces of mercury, fifteen ounces of axunge, and thirty-two ounces of olive-oil,—all taken by avoirdupois weight and none by measure;" and, adds Dr. Christison, I have corrected the College formula accordingly." And we accordingly find the following formula substituted in the Dispensatory for that of the Pharmacopoeia.

UNGUENTUM CITRINUM.

Take of Nitric acid (Dens. 1380 to 1390) nine fluidounces and a half;
Mercury, four ounces;

Axunge, fifteen ounces;

Olive-oil, thirty-eight fluidounces and a half;

Dissolve the Mercury, &c. &c.

It certainly is a remarkable fact that the errors here rectified should have appeared in two editions of the Edinburgh Pharmacopoeia. Dr. Christison, after alluding to the proper temperature for mixing the ingredients, and the use of almond and rape-oil and butter, as substitutes for olive-oil, proceeds to say," the other Colleges still follow the old faulty system; and the following will show how erroneous their proportions must be if Mr. Duncan be correct :

In this attempt to exhibit the proportions of other ingredients employed by the different Colleges with a standard quantity of mercury, the first assumption is, that nine fluidounces and a half of nitric acid of specific gravity 1390, are equivalent in strength to six fluidounces and a half of sp. gr. 1500; now these six fluidounces and a half weigh 4265 grains, of which four-fifths are real acid 3412 grains; nine fluidounces and a half of acid of sp. gr. 1390 weigh 5777 grains, containing 54.6 per cent. of real acid 3153 grains; but if 3412 grains of real acid are equal to six fluidounces and a half of nitric acid of 1500, 3154 grains fluidounces only, instead of 6.5 as stated in the table.

=

=

6

The proportion of acid of the London Pharmacopoeia is correctly stated, but not so the weight of the oil and lard; an imperial fluid ounce of olive-oil weighs about 402 grains, 16 fluidounces will consequently weigh 13.4 troy ounces, and these added to 24 troy ounces of lard will give only 37.4 ounces as the weight of these two ingredients, instead of 40, as

given in the table. This error appears to have arisen from considering 16 fluidounces of oil as equal to 16 troy ounces, for, added to the 24 ounces of lard, they make the stated quantity of 40 ounces.

=

With respect to the Dublin formula, five ounces and three-quarters of nitric acid of sp. gr. 1490 are used with four ounces of mercury, four wine pints of oil, and sixteen ounces of lard. Nitric acid of 1490 contains 76.5 per cent. of real, and five ounces, six drachms 2760 grains, therefore contain 2111 grains of real acid, which are equal to four fluidounces instead of only 3.83 as stated in the table. Taking the sp. gr. of olive-oil at 0.919, four wine pints or 64 wine fluidounces, will weigh 55.8 ounces troy, which added to 16 ounces of lard, will give 71.8 as their combined weight instead of 80 ounces.

The statement therefore exhibited by Dr. Christison, to prove "how erroneous" the other Colleges are, if his amendment of the Edinburgh and "Mr. Duncan be correct," should be altered as follows:

Morphia. With respect to the composition of this alkali Dr. Christison remarks that, "the analysis most confided in, that of Liebig, represents the anhydrous alkaloid to consist of 71.36 per cent. of carbon, 17.47 oxygen, 6.56 hydrogen, and 4.61 azote; which proportions approach nearly to the following constitution in chemical equivalents-C34 01 H° N = 372.08." Now it will appear by calculation, which it is not requisite to give, that the above-mentioned composition, instead of approaching that represented by the formula stated, would be more correctly denoted by C36, O7, H2° N, while C34 O13 H° N represents 55.92 per cent. carbon, 38.70 of oxygen, 1.62 of hydrogen, and 3.76 of azote, instead of the composition stated by Dr. Christison; but in accordance with the incorrect formula the equivalent of morphia is stated by Dr. C. to be 372.08.

=

8

On referring to Dr. Christison's statement of the composition of acetate of morphia, it would seem as if the figures representing the equivalents of oxygen and hydrogen had accidentally changed places in the formula which we have quoted; for he says that acetate of morphia" is probably composed of one equivalent of base, of acid, and of water (C34 H18 06 N+ A+ Aq.) that is, 372.08 parts of morphia, 43.28 acetic acid, and 9

O

In the formula already given, we have O13 H, and on referring to Liebig and halving the equivalents for hydrogen and azote, he gives C35 H1o 06 N, to which Dr. Christison's amended formula somewhat approximates; but then he has again given 372-08 as the equivalent, whereas it should be 288.08; it may be farther observed that, the equivalent of acetic acid is given as 43.28, instead of 51.48, which is shown at p. 8 of the Dispensatory to be its equivalent.

Under the head of Muriate of Morphia Dr. Christison has also given the more correct formula for morphia; and he states that," the constitution of the muriate of morphia is supposed to be one equivalent of the base, one of its acid, and six of water (C34 H13 O' N+ HCl + 6 Aq.), or

NEW SERIES, NO. II.-I.

K K

76.24, 9.66 and 14.1 per cent." Now this composition does not agree with the first, but with the second or more correct equivalent of morphia.

Dr. Thomson has also been most unfortunate in his statements respecting the composition of morphia, and has contributed his full quota towards the propagation of error; he makes the following statement: "Morphia consists of 1 eq. of anhydrous morphia 288.23+2 eq. of water = 18, making the equivalent 306.41. The anhydrous salt [alkali] consists of

=

The statement that morphia consists of itself and two equivalents of water, means, we presume, that the crystals of morphia are so constituted.

The account of the number of equivalents contained in morphia, was we suppose, intended to be a copy of Dr. Christison's very incorrect representation, in which as we have already pointed out, the equivalents of oxygen and hydrogen have changed places; but in addition Dr. Thomson has slipped in ten equivalents of hydrogen, and yet finds that the equivalent is only 372.23 instead of 382-23; and, notwithstanding the addition of these ten equivalents of hydrogen, we find the same erroneous representation of the composition of 100 parts of morphia as given by Dr. Christison. It is indeed impossible not to perceive the errors of the above statements on the slightest glance; thus, the oxygen is to the nitrogen, in the above statement, as 144 to 14.15, or about 10 to 1; but in 100 parts they are given as 17.47 to 4.61 or nearly as 4 to 1.

We shall not fatigue the reader with a statement of what the composition of 100 parts of morphia is according to Dr. Thomson's incorrect representation of its atomic constitution, but merely remark that as 71.36 per cent. of carbon should be 55.9, corresponding alterations would require to be made in the quantities of the other constituents; but it would be a waste of time to correct a part when the whole is so completely erro

neous.

=

=

With respect to the acetate of morphia, Dr. Thomson continues the error which he has committed, he says "acetate of morphia is a compound of 1 eq. of morphia 372.23 + 1 acetic acid 51.481 water 9, making the equiv. 432.91, or 82.95 parts of morphia + 14-15 of acetic acid and 2.55 of water 100 parts of the salt." Adopting 372.23 as the equivalent of morphia, and 51.48 as that for acetic acid, and 9 equivalent of water, the equiv. of acetate of morphia will be 432,71, and 100 parts of it will consist of 86.02 morphia, 11.89 acid, and 2.09 water, instead of the quantities stated by Dr. Thomson.

=

Similar errors occur with respect to hydrochlorate of morphia. crystals consist of one eq. of acid 36.42, and 6 of water

=

morphia

- 1

"The

372.231 of hydrochloric 54, making the equiv. 462-65, or 76.24 14.10 water, 100 parts." Now, ad

=

parts morphia +9.66 acid, and mitting as before the incorrect equivalent for morphia, 100 parts of the hydrochlorate must consist of 80.45 morphia, 7.87 acid, and 11.68 water,