I N D U X T R I A L A N D ENGINEERING C H E M I S T R Y
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compounds, the former attaining a maximum in half to one hour from the time of maximum pressure in the digester. Thereafter, their quantity seems to diminish. The lignin and methoxyl contents of pulps from cooks of different duration, expressed in percentages of those of wood are almost identical, thus showing that all the methoxyl is associated with lignin.
Vol. 15, No. 7
This study also shows that there is no advantage in cooking for longer than 2 hrs. a t 100 to 110lbs. per sq. in.
ACKNOWLEDGMENT The author is indebted to J. A. Staid1 and R. H. Grabow for supplying the samples and for all the data on the cooks other than the methoxyl determinations.
Consistency Determination of Greases' By Charles B. Karns and Oscar L, Maag RESEARCH LABORATORIFS OR
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THE
GALENA-SIGNAL OIL CO., F R A N K L I N ,
HILE it has been the practice for many years in classifying liquid lubricants to give consideration to their body in determining their value as a specified lubricant in connection with the service requirement, which body or viscosity is determined by instruments available for this purpose, the same cannot be said of solid lubricants such as greases. For many years greases have been used as lubricants, yet no instrument has been available to determine satisfactorily their consistency or body and thus furnish reliable data as to the general classification of greases for their many different requirements. The writers with this in mind have spent considerable time in developing a suitable apparatus which d l determine accurately the consistency or solidity of not only the soft greases, but the harder solid greases as well. This machine was developed principally for plant control in the manufacture of many kinds of greases, and has been successfully used in this respect for over a year, proving an important factor in the control of grease manufacture, as well as in designating the various grades of greases for general and special lubrication. By means of this apparatus it is possible t o classify greases similar to the way that viscosity classifies liquid lubricants such as oils. The apparatus is so constructed that by pressing a trigger a set of jaws opens and allows a ball of definite weight and diameter to fall a specified distance into the center of a standard cylinder containing the grease to be tested. The depth that the ball penetrates into the grease is measured in millimeters by a depth gage and recorded as the consistency or degree of solidity of the grease. For lubricants which are too hard to be determined in this manner, such as hard greases for railroad lubrication, the ball falls upon-a pin which is held by a disk in the standard cylinder centrally above the sample of hard grease contained in a small cylindrical cup. The depth in millimeters that this pin penetrates into the hard grease is recorded as its consistency. Consistencies determined by the ball falling directly into the grease are denoted by scale S, while readings procured by using the pin are designated by scale H, in order to distinguish results obtained by the two methods. The tabulated results of consistency determinations of typical greases that cover the hardness ordinarily encountered in these lubricants give an idea of the results obtained with this apparatus. The effect of temperature is quite noticeable on some greases-for example, a soft grease which had a consistency of 35.0, scale S, a t 75" F., gave a result of 22.5, scale S, a t 35" F. Also, a hard grease, such as used for railroad lubrication, which had a consistency of 7.5, scale H, a t 75" F., gave aresult of 3.0, scale H, a t 35" F. 1
Received December 25, 1922.
PA.
Consistency Taken MOTOR-CUP GREASES at 75' F. Heavy grade.. . . . . . . . . . . . . . . . . . . . . Medium grade... . . . . . . . . . . . . . . . . . Soft grade.. ...................... Especially soft lubricating grease.. . . 35.5 HARDGREASES FOR RAILROAD LUBRICATION No. 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . N o . 2 ............................ 9 . 0 Scale H No. 3 ............................ 11.5 7.5
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The writers have found the temperature of 75" F. to be very convenient for determining the consistency of most greases; however, for unusually soft greases a temperature of 35" F. is sometimes more satisfactory. I n order that different consistometers may give concordant results it is essential that the parts be thoroughly standardized in their manufacture. The writers are collecting data with this consistometer relative to the properties of various greases, which they will publish as soon as the work under progress is completed.
