324. METHODS OF ANALYSIS [Chap. 



43 REDUCING SUGARS AFTER INVERSION. -TENTATIVE. 



Transfer 50 cc. of the filtrate, obtained in 42, to a 100 cc. flask, add 5 cc. of con- 

 centrated hydrochloric acid and let stand overnight. Nearly neutralize with 

 sodium hydroxid solution, cool, dilute to the mark and determine reducing sugars 

 in an aliquot as directed under VIII, 25. Express the result as per cent of invert 

 sugar. 



44 SUCROSE.— TENTATIVE. 

 Proceed as directed under VIII, 1 8. 



45 TOTAL ACIDS.-TENTATIVE. 



Proceed as directed under XIX, 17, employing 5 grams of the sample. Express 

 the result as anhydrous citric acid. One cc. of N/'IO alkali is equivalent to 0.0064 

 gram of anhydrous citric acid. 



46 VOLATILE ACIDS.-TENTATIVE. 



Proceed as directed under XVI, 27, employing 25 grams of the sample, increas- 

 ing the amount of water used for the distillation and collecting a correspondingly 

 larger amount of distillate. Express the result as acetic acid. One cc. of N/10 

 alkali is equivalent to 0.0060 gram of acetic acid. Reserve the neutralized distillate 

 for the detection of butyric acid. 



BUTYRIC ACID. 



47 Qualitative Test. — Tentative. 



, Evaporate the neutralized distillate, obtained in 46, to dryness on a steam bath. 

 Decompose the residue with about 5 cc. of 10% sulphuric acid and note the odor. 



48 FIXED ACIDS.-TENTATIVE. 



Multiply the percentage of volatile acids, 48, by 1.067 and subtract the product 

 from the percentage of total acids, 45, to obtain the per cent of fixed acids as citric 

 acid. 



Micro-Analysis of Tomato Pulp, Ketchup, Puree and Sauce (Paste). 



49 apparatus. 



(a) Compound microscope. — Giving magnifications of approximately 90, 180 and 

 500 diameters. These diameters can be obtained by a microscope equipped with 

 16 and 8 mm. apochromatic objectives and a X6 and a X18 compensating ocular 

 (a X12 ocular may also be used if desired). 



(b) Thoma-Zeiss blood counting cell. 



(C) Special Thoma-Zeiss cell. — With the central disk of 19 mm. diameter for 

 making the mold count^. 



50 molds.-tentative. 



Clean the special Thoma-Zeiss cell so that Newton's rings are produced be- 

 tween the slide and the cover-glass. Remove the cover and place, by means of a 

 knife blade or scalpel, a small drop of the sample upon the central disk; spread the 

 drop evenly over the disk and cover with the cover-glass so as to give an even spread 

 to the material. 



