148 METHODS FOR THE ANALYSIS OF BLOOD 



brass collars for the nephelometer tubes into place, and fasten 

 on the plate from which the prisms were removed. Slip the mov- 

 able jackets into the holes in the cup supports, and after pushing 

 the nephelometer tubes into place in the collars, the instrument 

 is ready for use. A darkened room and a light-tight box for the 

 light are necessary. The box should be about 48 cm. long, 32 cm. 

 high, and 20 cm. wide for the ordinary colorimeter. It should 

 contain a bracket at one end to support the light (a 50-watt Mazda) 

 at the height of the nephelometer tubes, and a stop at the other 

 end, against which the instrument may be pushed and so placed 

 that the nephelometer tubes are about 30 cm. from the light. 

 A slot in the top of the box to receive the telescope of the instru- 

 ment and a dark curtain to cover the end of the box after the 

 instrument is pushed into place complete the equipment of the 

 box. All exposed parts should be painted a dull black. 



Since the readings obtained from suspensions of different 

 strength are not exactly proportional to the amount of precipitate 

 present, it is necessary to calibrate the instrument for different 

 strengths and make corrections accordingly. If. however, the 

 solution to be tested is within 25 per cent of the value of the 

 standard, no correction is necessary. 



ACETONE BODIES 



Nephelometric Methods of Marriott 1 



Principle. Acetone in very small amounts forms a cloudy 

 solution with the Scott- Wilson reagent which may be read nephelo- 

 metrically. By this method it is possible to make a complete 

 analysis for acetone and diacetic acid and hydroxybutyric acid 

 in from 2 to 5 c.c. of blood. 



Procedure. Two to 5 c.c. of blood drawn from a superficial, 

 arm vein by means of a sterile syringe are run into a small weighed 

 flask containing 50 c.c. of 0.5 per cent potassium oxalate solution. 

 The flask is reweighed. The diluted blood is run into 100 c.c. of 

 boiling water acidified with 1 c.c. of glacial acetic acid contained 

 in an 800 c.c. Kjeldahl distilling flask and the procedure is then 

 carried out as described in the Marriott-Scott-Wilson methods 

 for (a) acetone and diacetic acid and (6) /3-hydroxybutyric acid 

 1 Marriott: Jour. Biol. Chem., 1913, 16, 289. 



