86 REPORT—1845. 
that are formed under the influence of this law, when inorganic substances 
are introduced into the blood ; it remains even to be proved if the pheno- 
mena they give rise to are owing to the formation of any definite compounds 
between them and the elements of the blood and tissues. In the absence’ of 
all direct proof on this point, I would offer one or two considerations which 
would tend to indicate that the probability is in favour of the formation of 
definite compounds between the inorganic element and the blood and tissues. 
The researches of Mulder on the composition of albumen and fibrine 
prove, that the presence or absence of certain elements in very small pro- 
portions may essentially alter the properties of the protein compounds. The 
whole of the fibrine, for instance, in the blood of a small animal does not 
contain more than two grains of sulphur, which however appears to form as 
essential an element in its composition as it does in sulphuric acid ; if there- 
fore we introduce into the blood any substance which should deprive the 
fibrine of its sulphur, either by combining with the sulphur itself, or by re- 
placing it in the protein compound, we should immediately have a fluid cir- 
culating over the body which would not contain any fibrine, and which might 
be totally unfitted for carrying on the vital phenomena; two or three grains 
of baryta for instance, supposing it capable of producing such a reaction, 
would suffice to defibrinize the whole of the blood. Another consideration 
that would favour the supposition that isomorphous substances form certain 
definite analogous compounds with the blood and tissues, is, that we gene- 
rally find that the different substances belonging to the same isomorphous 
group give rise to certain physical changes in the blood which are readily 
recognizable ; thus the whole of the magnesian family agree in depriving the 
blood in a greater or less degree of its property of coagulation ; the same re- 
marks will apply to most of the other groups. It is highly probable that 
these physical changes are owing to the formation of certain definite com- 
pounds between the elements of the blood and the substances mixed with it. 
A careful analysis of the organs on which different classes of substances ap- 
pear more particularly to act, would probably elucidate this point. 
Before concluding, I would offer a remark on the relative poisoning powers 
of the substances that have been experimented with. The salts of palla- 
dium, platinum and baryta are those which prove fatal in the smallest doses ; 
and it is a curious fact, that, under an isomorphous point of view, these three 
substances are those which have the least analogy with the elements that 
enter into the formation of the animal solids and fluids ; on the other hand, 
arsenic, which might have been supposed to be rapidly fatal, is so inert when 
introduced into the blood that it will not speedily produce death, unless indeed 
it is injected in quantities sufficient to directly coagulate the blood. It re- 
mains for future experiments to determine if this is owing to its being iso- 
morphous to one of the elements of the fluids and solids, the phosphorous. 
On the Comet of 1843. By Dr. von Bocustawski of Breslau, Cor- 
responding Member of the British Association. 
[A communication made to the Mathematical and Physical Section at Cambridge, 
and ordered to be printed entire amongst the Reports.] 
Tue great Comet of 1843 was regarded with much interest by the whole 
world, more particularly by astronomers, and has left us some very import- 
ant questions to solve; that is, we require to know whether it be periodic 
or not, and the marvellous appearance of its magnificent tail should be 
