ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



523 



Fig. 106. 



,' 



The method of using the instrument is briefly as follows: — A 

 solution of blood (1 in 50, 1 in 100, or 1 in 200) is made by the 

 melangeur and put in the trough ; the latter is then placed in its 

 carrier and moved up or down by means of the milled head till the 

 precise point is reached at which the tint of the solution seen through 

 the central aperture exactly matches that of the coloured standard. 

 The figure is then read off by the index, and if the solution is 1 in 100 

 it will indicate direct the quantity of haemoglobin contained in 

 100 parts of blood ; but if the solution is 1 in 200 this figure must 

 be doubled, or if 1 in 50 halved. 



Thierry's Haema-Spectroscope.* — M. M. de Thierry designed this 

 apparatus for the detection of infinitesimal quantities of blood in any 

 fluid (water, urine, humours) or in spots on linen, wood, metals, &c. 

 The principle of the apparatus is based on the optical properties of 

 oxyhaemoglobin and reduced haemoglobin, one of 

 which gives two absorption-bands between the 

 lines D and E of the spectrum and the other a 

 single band between the others. 



It consists of a brass tube, in which slides 

 another tube of much smaller diameter, the 

 latter having a spectroscopic apparatus of new 

 design, furnished with a prism of great dis- 

 persive power and having a slit the width of 

 which can be regulated symmetrically on both 

 sides of the median line. Into the apparatus 

 can be introduced at will three glass tubes with 

 their ends closed by small glass discs. The 

 tubes are 1, 3, and 5 dm. long and 1 cmq. in 

 section. They hold the fluid to be investigated, 

 and accordftig to its richness in colouring matter 

 one or other of the tubes is taken. It can be 

 adapted either for a separate stand with a con- 

 cave mirror or more simply for an ordinary 

 Microscope. 



In use the mirror is adjusted so as to illu- 

 minate the tube strongly, and the opening of 

 the slit is regulated and focused so that the 

 spectrum is very clearly seen. The urine or fluid 

 in which the linen, paper, &c., supposed to be 

 spotted with blood has been previously macerated, 

 is placed in one of the tubes. If the fluid is 

 colourless or the colour is very faint the 5 dm. 

 tube is used ; if it is highly coloured it is diluted 

 with water, until it is of a bright rose colour 

 when seen through a pretty considerable thick- 

 ness and placed in the 1 dm. or 3 dm. tube. If the solution is too 

 highly coloured it will completely absorb the light, and consequently 

 the two characteristic bands will not be visible. 



Comptes Kendup, c. (1SS.5) pp. 1244-6. 



2 M 2 



