OXYH^EMOGLOBIN REACTIONS. 117 



short time examine them again with the spectroscope. No- 

 tice that when the oxygen has been removed by the ammo- 

 nium sulphid the spectrum has changed to that of haemo- 

 globin, which consists of one broad band in the space be- 

 tween that formerly occupied by the two. It is less dis- 

 tinct than the two bands of the oxyhsemoglobin spectrum, 

 but can be rendered darker by adding 3 or 4 drops of a 

 40-per-cent. solution of formaldehyd. 



247. Shake the reduced solutions with air and see 

 that the two bands have returned. If any ammonium sul- 

 phid remains the oxyhaamoglobin will be changed again to 

 haemoglobin on standing. 



248. Through the solution of blood pass a stream of 

 illuminating gas for a few minutes. The carbon monoxid 

 is absorbed, forming carbonic oxid haemoglobin. Examine 

 it with the spectroscope. It gives two dark bands much 

 like those of oxyhaemoglobin, though the one next the green 

 is not as wide as in the oxyhaemoglobin-spectrum. Try 

 now to reduce the compound to haemoglobin by means of 

 ammonium sulphid. The carbonic oxid is not expelled, 

 the two bands remaining unchanged. 



249. Prepare an alcoholic solution of guaiacum by 

 dissolving some of the gum taken from the middle of a 

 lump. No blue color is produced in the solution on the 

 addition of a small amount of old oil of turpentine or 

 hydrogen peroxid, but it is produced upon the further 

 addition of a few drops of blood. 



250. Try the same test on the scrapings from a po- 

 tato. A blue color is produced on standing, without the 

 aid of the turpentine or any similar oxidizing agent. 



251. Add a few drops of glacial acetic acid to diluted 

 defibrinated blood and warm gently. Haematin gives a 

 brown solution. Examine its spectrum. Neutralize with 



