I ABOPATORY MANUAL 
() 
EXERCISE NO. 1. 
Object: To properly clean laboratory equipment. 
Procedure: One of the most important, yet often neglected parts of the 
laboratory work of a dairy manufacturing plant,is the cleaning 
of glassware. Dirty glassware not only indicates slovenliness, 
but it is also conducive to inaccuracies in the work. If the glass¬ 
ware is properly cleaned immediately after use, it is very easy 
to keep clean. 
A. Bottles containing acid or milk should be shaken well when 
emptied so as to remove sediment and then rinsed out in clean, 
warm water, and filled with soap suds by submerging. With 
bottles about two-thirds full of soap suds, shake vigorously. 
Empty the bottles of the soap solution and rinse in clear warm 
water. Place aside to drain. Ordinarily the above procedure 
will maintain the glassware in a clean condition. 
B. If the treatment under A does not remove the scale on the 
inside of the bottle, pour into the bottle about 5 cubic centi¬ 
meters of the prepared cleaning solution and be sure it comes 
in contact with the scaled surfaces. Set the bottle aside for 
several minutes, and shake occasionally. Drain this solution 
from the bottles and proceed as under A above. 
Note: The cleanliness of Babcok glassware may be checked 
by running a blank test with clean water and suFuric acid, 
using the same proportions as in the milk test (See exercise 6). 
Observations: 
Conclusions: 
Questions: (1) If no cleaning solution is available what other methods 
can be suggested for removing scale from the inside of the bot¬ 
tle? 
(2) Enumerate several conveniences for use in washing glassware. 
(3) What is the average specific gravity of cow’s milk? 
(4) What is the weight of a charge of milk delivered by a 17.6 cc. 
pipette? Show by use of figures. 
References: F. & W. f 46, 47, 48; Van S. pp. 53-55, 175-176; Jud. 70-71. 
