COLLECTING AND PREPARING. 819 



passing over from the ammonia and acid bottles. The outgoing 

 tubes from the ammonia and acid bottles, begin at a distance above 

 the level of the liquid, or just below the bottom of the cork. Their 

 outer ends — preferably of two pieces each, joined by means of thin 

 pieces of india rubber tubing — end in drawn-out points of small 

 orifice. They should be so arranged that the orifices lie side by 

 side. This may be effected by passing the last joint of each tube 

 through two slightly converging holes in a cork. Long rubber 

 tubings instead of the pointed glass tubes, are often more easily 

 manipulated. Blowing into the mouth piece of the first wash 

 bottle will force the vapors of ammonia and hydrochloric acid 

 through their respective tubes, and as they issue from the con- 

 tiguous orifices they will combine into a fine white powder of 

 ammonium chloride which by proper adjustment may be made to 

 coat the specimen uniformly. It is desirable that the vapors should 

 be free from moisture. Therefore a U-tube filled with calcium 

 hydroxide should be inserted in the outgoing tube of the acid and 

 of the ammonia bottles. When not in use the apparatus should 

 be disconnected and the acid and ammonia bottles corked. 



Coating with ammonium chloride powder will be found very 

 serviceable in photographing fossils, as it gives them a uniform tint 

 and structures are not obscured by color. 



The powder is easily brushed off and will not injure the most 

 delicate specimens. 



LITERATURE. 



Various processes for special cases will be found described in the following 



articles, all of which have been freely drawn upon for this chapter. 



Bather, F. A. Preparation and Preservation of Fossils. The Museum's Journal, 

 Vol. VIII., pp. 76-90, September, 1908. 



Bernard, H. M. On the Application of the Sand-blast for the Development of 

 Trilobites. Geological Magazine, Dec, 4, Vol. I. (31), 1894, pp. 553-557. 



Grabau, A. W. How to Collect and Prepare Fossil Invertebrates. Bulletin Buf- 

 falo Society of Natural Sciences, Vol. VI., pp. 1 07-1 17, 1899. 



Keilhack, Professor Konrad. " Palaontologische Methoden," in Lehrbuch der 

 Praktischen Geologic, 2d edition, chapters 85 to 94, pp. 741-826, 1908. 



Moysey, Dr. L. On a Method of Splitting Iron Stone Nodules by Means of an 

 Artificial Freezing Mixture. Geol. Magazine, April, 1908. 



Schuchert, Charles. Directions for Collecting and Preparing Fossils. Smith- 

 sonian Institution, United States National Museum, Bulletin No. 39, Part K, 

 pp. 1-31, 1895. 



