480 Miscellaneous Intelligence. 



structed ; they are made of a mixture of baked and unbaked clay. 

 — Annales de Chimie, i. 469. 



28. On the Composition of simple Alimentary Substances^ by 

 Dr. Prout. — It is well known that Dr. Prout has of late years 

 devoted that portion of his attention which he gives to chemistry, 

 exclusively to the consideration of organized substances, with the 

 important object of making the knowledge he might obtain subser- 

 vient to the study of physiology and pathology ; and during the 

 last session of the Royal Society, a paper by this philosopher was 

 read, containing many important and apparently accurate results 

 relative to the particular subjects which he has pursued ; some 

 account of which we are desirous of giving in this place. 



Dr. Prout*s first object was to devise, if possible, an unexcep- 

 tionable mode of determining the proportions of the three or four 

 principles, which, with few exceptions, form organic bodies ; and 

 after numerous trials, he adopted a method founded upon the fol- 

 lowing well known principles. When an organic product, contain- 

 ing three elements, hydrogen, carbon, and oxygen, is burnt in 

 oxygen gas, one of three things must happen : i. The original 

 bulk of oxygen gas may remain the same, in which case the hydro- 

 gen and oxygen in the substance must exist in it in the same pro- 

 portions in which they exist in water ; or, ii. The original bulk 

 of the oxygen may be increased, in which case the oxygen must 

 exist in the substance in a greater proportion than it exists in 

 water ; or, iii. The original bulk of the oxygen gas may be 

 diminished ; in which case the hydrogen must predominate. 

 Hence it is obvious, that, in the first of these cases, the composition 

 of a substance may be determined, by simply ascertaining the 

 quantity of carbonic acid gas yielded by a known quantity of it ; 

 while, in the other two, the same can be readily ascertained by 

 means of the same data, and by noting the excess or diminution of 

 the original bulk of the oxygen gas employed. 



The apparatus consists of two inverted glass syphons which act 

 the part of gasometers ; these are connected when required, by a 

 small green glass tube, in which the substance is to be decomposed 

 and burnt : the syphons are very carefully gradated ; so that the 

 quantity of gas in them can be accurately estimated ; and are sup- 

 plied with cocks both above and below, so that they can be filled 

 with mercury, the mercury drawn off and gas introduced, the gas 

 transferred through the green glass tube, or the contents retained 

 in an undisturbed state, with the utmost readiness and ease. The 

 substance to be decomposed, may be put into a platina tray, and 

 introduced alone into the green glass tube, and being there heated 

 by a spirit lamp, be burnt in the gas passing over it ; or it may 

 be mixed with pure siliceous sand ; or, what is most generally pre- 

 ferable, be mixed with peroxide of copper, which is always left, in 

 consequence of the excess of oxygen gas used, in the state in which 

 it was introduced. After the experiment the volume of gas is easily 



