820 



ORGANIC ANALYSIS. 



48-73 grs. of acetate of silver left 

 31.49 grs. of metallic silver. 



17.24 grs. will therefore express the loss, 

 due to the united weight of acetic acid and 

 oxygen combined with the silver. 



^ Equ.ofsil. 

 31.49: I 108 :: 17.24 : x (=59) 



t 1 equ. oxy. 



59 I 8 = 51, the equivalent num- 

 ber of acetic acid. 



Another example will shew the method of 

 calculating the number of equivalents of each 

 element in the compound. 



By analysis with oxide of copper we find 

 10 grs. of acetate of silver yield 



5.277 grs. of carbonic acid and 

 1.620 grs. of water 

 and calculating from the 



previous experiment. . 6.462 silver, 

 this is equivalent to .... 1.439 carbon 



180 hydrogen 

 The deficiency is 1919 oxygen. 



10.000 



Then by proportion 



Silv. 

 6.462 



Eq.sil. 

 108 



6.462 : 108 



6.462 : 108 



Carh. C. 



I 1.439 : x (=24), or 4 



Hydrog. H. 



0.180 : .r (= 3), or 3 



Oxygen O. 



1.919 : x ( 32), or 4 



Total.. =59 

 deduct 1 equivalent of oxygen 8 



and we obtain the equivalent 

 of anhydrous acetic acid. . 



51 



rC4 



,oJ H3 



[03 



Sometimes no compound with silver can be 

 obtained, and a salt of lead is then, if prac- 

 ticable, substituted for it. The residue, how- 

 ever, in this case does not consist entirely of 

 metallic lead, neither is it all oxide of lead. 

 It is carefully weighed, treated with acetic acid 

 in the crucible itself; the oxide of lead is thus 

 dissolved and washed away. When the con- 

 tents of the crucible have been carefully dried, 

 a second weighing gives the quantity of me- 

 tallic lead, whilst the loss furnishes that of the 

 oxide. From the metal we calculate the quan- 

 tity of oxide to which it is equivalent ; this 

 added to the portion dissolved by acetic acid 

 furnishes the whole quantity of oxide con- 

 tained in the compound : a calculation similar 

 to that employed for the silver salt, then sup- 

 plies us with the means of determining the 

 equivalent number of the body analysed. This 

 method is not quite so accurate as the preceding; 

 it involves more manipulation, and the com- 

 pounds of lead are apt to undergo slight loss 

 by volatilization at a high temperature. 



It would here be out of place to enter into 

 detail into the methods of checking the cor- 

 rectness of an analysis in its various parts. 

 Upon this point the reader is referred for in- 

 formation to Liebig's Introduction to Organic 

 Analysis. The subject is an important one, 



and by no means sufficiently attended to by the 

 majority of those who devote themselves to 

 analytical researches of this description. 



The number of authors who have written 

 upon the methods of analysis is very great; 

 and their instructions are found more in de- 

 tached papers, scattered through the various 

 scientific periodicals than in systematic treatises. 



The works which may be consulted with espe- 

 cial advantage on proximate analysis are Berze- 

 lius's Lehrbuch Der Chemie, third German 

 edition, translated by Wohler, lOvols. 8vo.; the 

 fourth edition of Prout's Treatise on Diseases 

 of the Stomach and Urinary Organs, and his 

 papers in theMedico-Chirurgical and Philoso- 

 phical Transactions; G.O. Rees on the Analysis 

 of Blood and Urine ; Lecanu, Ann. de Chimie, 

 xl viii ., and various papers on the blood ; Simon, 

 Handbuch der augewandten Medizinischen 

 Chemie, 2 vols. 8vo. 1840-42 ; one of the 

 most recent and best treatises on animal che- 

 mistry, full of laborious and careful analyses, 

 with copious and accurate directions for their 

 performance. This work is now being trans- 

 lated into English. 



For directions for analysing the inorganic 

 constituents of organized compounds the reader 

 is referred in particular to Rose's Analytical 

 Chemistry, either the fourth German edition, or 

 the English translation of the first edition by 

 Griffin. 



Ample instructions for the ultimate analysis 

 of organic substances are furnished in Liebig's 

 Organic Analysis, translated by Gregory, and 

 forming one of the series of works published 

 in Griffin's Scientific Miscellany, and in the 

 fifth volume of Dumas' Traile de Chemie 

 Appliquee aux Arts, as well as in the volumes 

 of Berzelius already referred to. 



A valuable treatise has recently been pub- 

 lished in German by Vogel, juo. on the ap- 

 plication of the microscope to the field of 

 animal organic chemistry " Anleitung zum 

 Gebrauche des Mikroskops zur Zoochemischen 

 Analyse und zur Mikroscopisch-chemischen 

 unlersuchung uberhaupt." 



(W. A. Miller.) 



OSSEOUS SYSTEM. (COMPARATIVE 

 ANATOMY.) One of the most striking and 

 distinctive characters peculiar to the highest 

 grades of animal existences, the VEHTEBRATA, 

 is that they have their bodies supported by, 

 and as it were moulded upon, an internal 

 frame-work, which is generally made up of 

 numerous pieces, very various in their forms 

 and uses, which are called the bones ; and the 

 assemblage of them, whatever their modifica- 

 tion, constitutes the skeleton. 



Seeing the great diversity of forms and habits 

 in the innumerable races of animals constituting 

 this great group of living beings, some being 

 specially appointed to occupy the waters of 

 our globe, others to inhabit the marsh and the 

 swamp, whilst others again tread the firm sur- 

 face of the ground, or raise themselves into 

 the regions of the thin air; and that under all 

 the diversified shapes of Fishes, Reptiles, Birds, 

 and Mammifers, we are prepared, a priori, to 



