Gerardus Johannes Mulder (1802-80)

On the composition of some animal substances

Journal für praktische Chemie 16, 129 (1839) [as translated and excerpted in Mikulás Teich, A Documentary History of Biochemistry, 1770-1940 (Rutherford, NJ: Fairleigh Dickinson University Press, 1992)]

I have been occupied for some time with the study of the most essential substances of the animal kingdom, the fibrin, the albumin and the gelatin. Since the publication of this work I continued to study these substances. Berzelius communicated with me concerning the published results and gave me good advice for which I express my sincere thanks. ...

In my former experiments I did not consider the sulphur and phosphorus, which are found as integral parts of these bodies. ...


From the results quoted it can easily be concluded that in fibrin and in the egg albumin there is always 1 atom of sulphur to 1 atom of phosphorus, whilst with the serum albumin there is 1 atom of phosphorus to 2 atoms of sulphur.

We calculate now the atoms of the complex bodies according to the smallest atom number of the sulphur and phosphorus, thus we can describe the composition of these three bodies in the following way:

Fibrin and egg albumin[1]
Serum albumin
These enormous number can be justified if it can be shown that SP binds with a quaternary organic body which has the composition C400H620N100O120, in order to form fibrin and the egg albumin, whilst binds with the same body to form the serum albumin.[2]


The organic substances which is present in all constituents of the animal body, also as we shall soon see, in the plant kingdom, could be named protein from πρωτειος, primarius. Fibrin and the egg albumin thus have the formula + , the protein of the serum albumin + .


It appears that animals draw their most essential nutrient ingredients directly from the plant kingdom. It is possible that the plant protein contains sulphur and phosphorus in a different relation from that in the animal protein which contains fibrin and so on, but the quaternary organic body is the protein itself.

The plant-feeding animals are thus, considered from this point of view, not different from the flesh-eating. Both are nourished by protein, by the same organic body, which plays a principal role in their economy. It remains still to know whether the starch and other substances, which are recognized as nutrient substances, in the animal body can be changed into protein.

The nourishing capacity of bread and other nutrients which contain protein is thus easily understood. They offer, unless the digestion works an alteration here, directly one of the most important parts of the animal body.


VIII. Proteinsulphuric acid ...

The body thus has the following constitution:

Sulphuric acid8.341501.178.31

[1]The columns of the table represent, respectively, the element, the number of atoms (effectively defining an empirical formula), the weight of that number of atoms (on Berzelius' scale of O = 100), and the mass percent. --CJG

[2]Barred sulphur () represented, in effect, double atoms of sulphur. --Teich

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