TESTING MII.K AND CREAM FOR ACID 595 



is not feasible for the average creamery which has no chemical 

 laboratory, and no skilled chemist, to weigh out the dry sodium 

 hydroxide and to make up the desired strength solution from it. 

 Attempts to do this work under ordinary creamery conditions almost 

 invariably result in alkaline solutions that are not of standard 

 strength and that yield erroneous tests. 



The creamery may, however, purchase standard alkaline solu- 

 tion of a strength suitable to be used without further dilution, or it 

 may purchase a concentrated standard alkaline solution which can 

 be diluted in accordance with the directions furnished on the bottle, 

 or it can purchase the chemically pure, dry sodium hydroxide of 

 exact known weight and dissolve the contents of the entire package 

 in the necessary amount of distilled water, or the sodium hydroxide 

 may be purchased in the form of tablets of known strength, which, 

 when dissolved in a given amount of water, produce the desired 

 standard solution. 



Any of the above enumerated forms of alkali will yield standard 

 alkaline solutions, when purchased from a reliable supply house, 

 when diluted with or dissolved in the correct amount of distilled 

 water, or rain water, or other water free from alkalies or acids, and 

 when care is taken that all of the alkali contained in one and the 

 same purchased container is used and that none of it is spilled. For 

 creameries that are not equipped with a chemical laboratory and that 

 do not have the services of a skilled chemist the purchase and use 

 of sodium hydroxide in any of the forms enumerated above will 

 generally place at their disposal uniformly accurate alkaline solu- 

 tions. 



For creameries that maintain their own chemical laboratory, 

 the following method, devised by Hunziker and Hosman, 1 may as- 

 sist in the further "fool-proofing" of tenth normal alkali solutions : 

 Use a common large stock bottle, a two gallon bottle, such as can 

 be readily purchased from and easily replaced by any drug store. 

 These bottles, when filled to just below the neck, hold 7500 cubic 

 centimeters. Fill them with water to the 7500 c.c. mark and mark 

 the 7500 c.c. level by a scratch on the shoulder of the bottle with a 

 file. Crush in a mortar, or otherwise, sodium sticks and weigh 30 

 grams of the crushed sticks each into glass tubes. The tubes should 



i Hunziker and Hosman, A Practical M'ethod for the Preparation of Accu- 

 rate NAOH Solutions for Acid Tests. Blue Valley Research Laboratory 



