1813.] Definite Proportions in Chemical Combinations. 115 



Oxides. Corresponding Sulphurets. 



Deutoxide of iron Magnetic pyrites. 



Deutoxide of tin Mosaic gold. 



Deutoxide of lead Common galena. 



Peroxide of lead Persulphuret of lead. 



Oxide of zinc Sulphuret of zinc. 



Oxide of bismuth Sulphuret of bismuth. 



Deutoxide of antimony Sulphuret of antimony. 



Deutoxide of arsenic Orpiment. 



Protoxide of manganese Sulphuret of manganese. 



Deutoxide of molybdenum . . . .Sulphuret of molybdenum. 



Potash Sulphuret of potassium. 



Soda Sulphuret of sodium. 



(To be continued.) 



Article IX. 



Remarks on the Measurement of Minute Particles, especially 

 those of the Blood and of Pus. From Dr. Young's Medical 

 Literature, 8vo. Lond. 1813, p. 545. 



I. On the Form and Magnitude of the Particles of the Blood. 



The form and magnitude of the coloured particles of the 

 blood is a subject not only interesting and important in itself, but 

 is also capable of assisting, by means of comparative observa- 

 tions, in the determination of the magnitude of the capillary 

 arteries, and the investigation of the resistance which they ex- 

 hibit ; it may also be of advantage to obtain some tests capable 

 of ascertaining, whether these particles undergo any change in 

 diseases of various kinds, and what is their relation to the glo- 

 bules of pus, and of other animal fluids : hitherto the measures 

 of the particles of blood, which have been considered by various 

 authors as the most accurate, have differed no less than in the 

 ratio of - to 5 ; and there is an equal degree of uncertainty 

 respecting their form, some admitting the truth of Mr. Hewson's 

 opinions, and a greater number rejecting them without any satis- 

 factory evidence. In such examinations, it is only necessary to 

 employ a full and unlimited light, in order to obtain a very dis- 

 tinct outline of what appears manifestly to be a very simple 

 substance, and we thus seem to have the clear evidence of the 

 lenset against Mr. Hewson: but we must remember, that where 

 the substances to be examined are perfectly transparent, it is 

 only in a confined and diversified light that we can gain a cor- 



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