82 The Microscope. 



in time, however, become so brittle that a slight jar may send 

 the cover and the object flying from the slide. To prevent this, 

 gold size has been highly recommended. 



In the article already referred to, Mr. Dienelt further says: 

 "Gold size is slow in drying, but if one builds a number of cells 

 to-day, they will be exactly a month old a month from now, and 

 in time will get hard as glafs. Make them with one or two, sel- 

 dom three, successive coats, and always aim to have a lot of old 

 cells on hand." When the}^ are to be used, a thin coating of the 

 size is added to the ring, the object arranged in the cell, and the 

 cover applied to the soft surface of cement, and a finishing ring 

 added at the edge, with colored rings, if desired, when all is dry. 



Mr. John Phin,in his little book "How to Use the Micro- 

 scope," says in reference to gold size : " The most extraordin- 

 ary recipes have been given for the preparation of this cement, 

 which is in reality nothing but good linseed oil rendered very 

 drying by the usual methods. Gilders frequently make it into 

 a semi-paint by adding coloring-matter, thus forming a ground 

 of a shade similar to the gold they use, and this seems to have 

 misled some of our best writers. There is no ochre, litharge 

 or anything ot the kind present in good gold size. It does not 

 pay to prepare gold size in small quantities, and it may be 

 obtained from any color dealer. The older it is the better, and 

 it is well, therefore, to lay in a good stock, which must be kept 

 carefully corked. The working supply should be kept in a 

 small bottle. This is the favorite cell-making material emplo3^ed 

 by Dr. Carpenter, and it is certainly the most trustworthy 

 cement that we have. It adheres firmly to glass, and if laid on 

 in thin successive coats, tolerabl}^ deep and very durable cells 

 may be built up, but the process requires considerable time, 

 otherwise the under layers will remain soft. It has this great 

 advantage over asphalt, dammar, and other cements composed 

 of solid materials dissolved in some menstruum, that fresh coats 

 have but verj slight action on the old layers on which they may 

 be laid. It mixes with turpentine, and consequently with most 

 materials soluble in turpentine, but when once dry and hard 

 turpentine, alcohol, ether, etc., have little action on it. It does 

 not mix with alcohol, and therefore cannot be mixed with the 

 solution of shellac in alcohol in any of its forms." Mr. Phin is 

 probably wrong in saying that the cement contains no lead nor 



