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known among the chemists of this country; and therefore all that remains for us is to give a brief view of the manner in which M. Gay-Lussac treats the subject. He begins with an account of the properties of iodine, and then proceeds to its combination with simple bodies ; especially those processes in which the iodine is made to unite with hydrogen so as to form the hydriodic acid, according to one hypothesis, or, according to the other, loses a part of its oxygen. We are next furnished with a description of many of the iodurets, and of the action of iodine on various oxyds, which leads to an account of the iodic acid and its compounds, particularly with chlorine; and then we have a view of the hydriodates, given much in detail, and with every appearance of great accuracy.

Some remarks on chlorine follow, especially as being a body in many respects analogous to iodine. We quote a paragraph towards the conclusion, referring to the hypothesis which has given rise to so much discussion :

• From the analogies which I have established in this memoir, we shall be convinced that oxygen, chlorine, and iodine, do not form an insulated groupe to which the acidifying property exclusively belongs. We have seen that it also belongs to sulphur and to azote, and we may say that it appertains likewise to a number of other bodies. Nevertheless, oxygen will always be considered as the principal acidifying substance, not only by the energy of this property and by the numerous acids which it forms, but because we can employ as solvents only those fluids which, containing oxygen and hydrogen, can change the nature of the compounds which they dissolve. Although chlorine does not disengage oxygen from all its combinations, it appears to me, that it ought to be placed before it, on account of the energy of its properties : but fuorine, which we have not yet been able to obtain in an insulated state, would without doubt be placed before chlorine, because it disengagés oxygen from all its combinations. We owe to M. Ampere the first idea that the fluoric acid is analogous to the hydrochloric acid; that is to say, that it is composed of hydrogen and a particular body analogous to chlorine, which he had proposed to name fluorine. Mr. Davy, to whom he had imparted the theory which he had conceived, did not seek to verify it until a long time afterward, when M. Ampere had answered the objections which had been addressed to him.'

Exposition of the Facts collected up to the present Time on the Effects of Vaccination; and an Examination of the Objections that have been urged against it at different Periods, and which some Persons still allege against the Practice of it. By MM. BERTHOLLET, Percy, and HALLÉ. - In this paper,

hich terminates the volume, the reporters observe with justice and candour that, notwithstanding the almost unanimous testimony of medical men and the public in general in

favour of vaccination, come objections are still raised against it; and that, as these do not appear, at least in some cases, toi originate in any unworthy motive, it is proper that they should be examined with impartiality. They mention five objections that are occasionally urged: but the only one of them that, in this country, is regarded as of the least moment, or has any effect on the public mind, is that vaccination leaves in the constitution a tendency to eruptive complaints of various kinds. The circumstances which attended the first employment of the vaccine matter by Dr. Woodville, at the Small-pox Hospital in London, where eruptions were produced in a great number of cases, may have been a cause for the opinion that they were a necessary consequence of the disease: but the source of the evil in this case is well known, and was very candidly acknowleged by Dr. Woodville. Or this topic, generally, it is here remarked :

" From the comparison which we have made between the observations cited and the sum of the observations collected, relatively to the eruptions that have accompanied vaccination, we conclude that the cases in which these eruptions, as well as the febrile affections that have taken place, compared with the cases which are exempt from them, are in such a proportion that we cannot attribute these eruptions to the vaccine virus, nor regard them as a consequence of its properties; that they must be referred to accidental circumstences, either general or particular; that these circumstances, which cannot be always appretiated in many insulated individual cases, have in most of them, and especially in those in which the phænomena have shewn themselves at once in a great number of individuals, a relation to variolous emanations concentrated in those places in which the vaccination has been performed, or with the contagion of the epidemic small-pox; that, consequently, they do not prove in any way that the vaccine virus carries into the body a ferment which ought to be expelled by a febrile commotion, and by a particular eruption, or by any other remarkable evacuation ; and that we have a right to draw directly the contrary conclusion from the number of cases in which the vaccine matter inserted has not produced any sensible change, except in the very place of the insertion, and · has not given occasion to any durable febrile commotion, or to any appretiable inconvenience.'

The objection which, we think, has had the most influence in this country is not noticed in the Report ; viz. that the vaccine inoculation, although it may be a complete preservative against the small-pox when it is first performed, loses this preservative power after some time. Our readers must be well aware that this allegation has been made by 'some professional men, and with a certain degree of plausibility; and at one time it appeared to be gaining ground even among


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