348 REPORT OF NATIONAL MUSEUM, 1899. 



Mention may be made here also of the material .sold in the shops 

 under the name of Bon Ami and used for cleansing glass and other 

 like substances. This under the microscope shows abundant minute 

 sharply angular particles, consisting of partially decomposed feldspar 

 mixed with a completely amorphous mineral which may be opalescent 

 silica or possibl}' a very finely comminuted pumice. An analysis by 

 Packard in the laboratory of the Department yielded: 



Silica - 59.86 



Alumina 18. 74 



Magnesia 0. 34 



Potash 10. 70 



Soda - 3. 51 



Ignition 7. 67 



Total , 100.82 



Alcohol extracts 7.43 per cent, and water 0. 244 per cent in addition, 

 the extract having a soapy appearance and the odor of some essential 

 oil. 



A soapy clay occurring near Rock Creek station, in Albany County, 

 Wyoming, has been shipped in con,siderable quantities during the past 

 few years to New York, Philadelphia, and Chicago, but the use to 

 which it was put remains a secret. It is stated ^ that at first the mate- 

 rial was sold at the rate of $25 a ton, but that the price has now 

 dropped to |5 a ton. Analyses are given as below. The chief 

 physical characteristic of this clay, aside from its soapy feeling, is its 

 enormous absorptive power, the absorption being attended naturally 

 with an increase in bulk amounting to several times that of the origi- 

 nal mass.^ Plate 17, lig. 11 shows the extreme fineness and homoge- 

 neity of this clay as seen under the microscope. 



a No estimate. 



b NaO. 



1 Engineering and Mining Journal, LXIII, 1897, p. 600; LXVI, 1898, p. 491. 



2 A small plug of this clay fitted to accurately occupy a space of 20 cubic centi- 

 meters in the bottom of a conical measuring flask, and kept saturated with water for 

 two days, swelled to a bulk of 160 cubic centimeters. The absorption was so com- 

 plete that none of the water ran off when the flask was inverted, and the condition 

 of the clay resembled that of flour or starch paste. 



