1892.] • MICROSCOPICAL JOURNAL. 197 



sharp, angular outline. These are probably due to the vitrifac- 

 tion of some portions of the cement material." 



VII. Mihcaztkee Cement. — "■ There is little, if any, distinct- 

 ness in the individual particles, which are collected in opacjue 

 masses, and the particles, which are collected in opaque masses, 

 and the particles themselves are almost entirely opaque. This 

 cement did not give as good results as the others mentioned." 



No preparation is necessary except to sprinkle a little of the 

 dry cement upon the slide — " and examine it with an objective of 

 considerable power." 



The article is illustrated with a number of plates, but they can- 

 not show as the slides do. A number of these plates show the 

 cement after it has been mixed with a little water and allowed to 

 set upon the slide. From this no special preparation is neces- 

 sary. 



Natural cements are those " in which the burning process has 

 not been carried to the point of vitrifaction, while Portland ce- 

 ments are those which have been vitrified by burning." 



Below is given a table showing the pounds per square inch re- 

 quired to crush briquettes made from the cements, as reported 

 by Mr. M. I. Powers, another student of the same university : 



Order given by Mr. Powers. Order given by Mr. Browu. 



Buckeye, Portland Artificial Cement. ..Bellefontaine, Ohio.. .650 pounds... Buckeye. 



Gibbs" Portland " " ...Grays Essex, Eng....350 " ...Gibb.s'. 



Soutli Bend " " ...South Bend, lud 



Hoflinau's Rosendale... Natural Cement. ...Kingston, N. Y 310 " ...South Bend. 



Utica Black Ball " " ...La SaUe. Dl... 280 " ...Eo.sondale. 



Milwaukee " " ...Milwaukee, Wis 120 " ...Utica Black Ball. 



J. Clark's Utica " " ...Utica, HI 70 " ...Milwaukee. 



Although the table is not quite complete, it is easily seen that 

 the order of strength, as found by crushing briquettes, is nearly 

 the same as the order of quality determined by the microscope. 

 The only marked difference is between the Milwaukee and the J. 

 Clark's Utica cements. Possibly the specimen of cement used by 

 Mr. Brown was not up to the same standard of quality as that 

 used by Mr. Powers. 



Dunkirk, N. Y., July 12, 1892. 



Mounting Trichinae. — With your permission I would like 

 to suggest to Messrs. Whelpley and Farr (queries 32 and 43, June 

 number) a method for mounting trichinous muscle which I have 

 found very successful. Macerate a small piece of the muscle in 

 cold water for a day, now tease it out with needles and place be- 

 tween two slides and bind with stout thread ; immerse in alcohol 

 about 95% for about ten minutes, then separate slides and transfer 

 muscle to oil of lajeput ; let it stand here for two or three days and 

 mount in balsam, when they will find the trichinae will not " dis- 

 appear," nor will they shrink as I have had them do in time after 

 having used the alcohol solution for a longer time. 



W. N. Preston. 



Gum for Slide Labels. — Dissolve 2 grams of aluminum 

 sulphate in 20 of water. Mix the solution with 250 grams of 

 strong mucilage (2 of acacia gum to 5 of water). The alumi- 

 num sulphate greatly increases the adherent properties of the 

 STum. 



