KING'S COLLEGE HOSPITAL
444 duction of this cloudiness, in solutions of arsenious acid, has frequently been noticed. I am not aware that any attempt has been made to account for it. I have satisfied myself that it arises from the presence of arsenic acid, produced in these solutions, as I have already explained, by exposure to the air. The arseniate of silver, in its ordinary form, no doubt is of a deep-brown or red; but the colour varies greatly with the state of dilution of the fluid: when concentrated it is of a
... rated it is of a reddish-brown; when more dilute, brick-red; when still more dilute, greyish; and when extremely dilute, as Tu-01-o-, a whitish cloud, exactly similar to that which is observed in solutions of arsenious acid, after they are kept for some time. Postscript.—1. In Reinsch's process, if the arsenious acid exceeds one-fiftieth of a grain to one square inch of copper surface, the arsenical deposit is apt to peel cff, and, when the fluid is muddy, may be lost, unless the process is closely watched. The scales thus detached do not consist exclusively of metallic arsenic; they contain a large proportion of metallic copper. This proportion I have never found less than sixtyfive per cent; sometimes it is considerably greater. 2. When these scales are heated in a test tube, a considerable quantity of arsenious acid sublimes in the usual crystalline form, but there is always a large residue unsublimed, consisting chiefly of oxide of copper, but containing also about one-half of the arsenic, apparently in the state of sub-arseniate of copper, with slight traces of sub-arsenite. The presence of the arsenic acid in the residuum may be easily shown by boiling it with solution of carbonate of potash, filtering, neutralizing it accurately with nitric acid, and then adding solution of nitrate of silver, which gives a precipitate of red arseniate of silver. 3. A similar result is obtained when copper-foil coated with arsenic is heated in a test tube over a lamp. One-half only of the arsenic sublimes in the state of arsenious acid. RESIDENT MEDICAL OFFICER TO THE LOUGHBOROUGH DISPENSARY. ON March 31st last I vaccinated Marianne W-, aged three years, a perfectly healthy child. When next seen, on April 7th, I was told that on the very day (April 1st) following vaccination she became very sick, vomiting frequently, and feverish. On the evening of the next day (April 2nd) the mother fancies that there was a little redness about the chin, which however on the 3rd April assumed the aspect of decided papulæ over the whole face, arms, legs, and body. I now ascertained that at the school to which the child had gone up to the day of its being taken ill two or three of the scholars had had the small-pox about a month ago, and had returned among the other children some few days back. April 7th.-The vaccine vesicles (seventh day) are larger than the variolous, very little elevated above the cuticle, irregular in shape, being not perfectly circular, but flattened and indented, and lobulated at the edges. There is evidently very little fluid in them, and no appearance of areola. The whole body is marked with distinct variolous vesicles, (fifth day,) having the same flattened aspect as, but smaller than, the vaccinia ; and being so little elevated above the surface, they do not present that "shotty" feel so characteristic of variola, especially in its papular stage. Febrile action slight. 9th.-The variolous eruption (seventh day) is more turgid; that on the face is pustular, and a few of the pustules are beginning to scab; that on the arms is hemispheroidal, prominent, and pustular; that on the legs is opaque, but not distinctly pustular; the central depression still existing in some of the vesicles. The vaccinia (ninth day) is not more elevated, though the fluid seems more opaque; the vesicles are now about half an inch in diameter, but still present that irregular, indented appearance round their margin, external to which there is now an areola of about one line in diameter, as there is also around each variolous pustule. The variolous vesicles in the immediate neighbourhood of the vaccinia are much smaller and less opaque than elsewhere, neither are they so turgid or spherical as in other parts of the body. The mother attributes this to the child always lying on that side, (the right,) and certainly the left arm (which, however, by some oversight was not vaccinated) presents well-filled vesicles; the eruption of the right leg also is somewhat less prominent than that on the left, though certainly there is not that marked difference observable in the vesicles of the two arms. 10th.—Variolous eruption (eighth day) entirely pustular, scabbing going on in the face. Areola of vaccine vesicles (tenth day) no larger, though the vesicles themselves are larger, and beginning to lose their indented margin. The variolous eruption around vaccinia is now pustular. 12th.-Scabbing progressing on the face, (tenth day,) and the pustules on the arms shrivelling up; no secondary fever. A scab perceptible (twelfth day) on each vaccine vesicle; no in. crease of areola, nor is there any surrounding induration. 14th.—Some of the pustules on the legs shrivelling, (twelfth day.) Vaccinia (fourteenth day) scabbing, the scabs being rather conical, and of a dirty light brown in colour; no increase of areola. 16th.-All the pustules of the legs shrivelling, (fourteenth day.) Scabs of vaccine vesicles (sixteenth day have fallen off, leaving an irregularly circular, purple-red mark, larger, though otherwise similar, to the stains of the variolous eruption ; the vaccine stains are perfectly flat and smooth, without the slightest indication of the small depressions and radiating lines characteristic of a good vaccine cicatrix. 19th.-The whole body presents purple-red stains. Remarks.-Considering vaccinia as a disease sui generis, we have here two exanthemata co-existing in one person, and each by its presence modifying, but not superseding, the regular course of the other.