1882.J 



MICKOSCOPICAL JOUKNAL. 



113 



carefully, with good effect, weak liquor 

 potassa instead of carbonate of soda. 

 The material is then ready for the 

 acids. If in haste, I at once boil the 

 material in a solution of carbonate of 

 soda, or even dispense with this and 

 treat it with the acids. But the wash- 

 ings and boiling in the solution of 

 carbonate of soda remove a large 

 quantity of organic matter and save 

 acids. 



When ready for the acids, I shake 

 the material well in water, pour a 

 certain quantity into a beaker, allow 

 it to settle, and drain off the unsettled 

 portion. I then add muriatic acid in 

 about the following quantity : If the 

 material occupies half an inch in depth, 

 I add one-quarter to one-half an inch 

 in depth of the acid. I then add one- 

 third to one-half as much nitric acid, 

 and stir the whole with a glass rod, 

 or a strip of glass, when, placing 

 the beaker on one of the rings of the 

 retort-stand, on which has been fasten- 

 ed a piece of wire gauze to prevent 

 the flame of the lamp from coming in 

 direct contact with the beaker, the 

 material is boiled for a few minutes, 

 five perhaps, seldom ten, and while 

 boiling, finely powdered chlorate of 

 potash, or finely powdered bichromate 

 of potash, is slowly added till efferves- 

 cence nearly or quite ceases, but 

 the quantity used is much a mat- 

 ter of judgment. A good deal of 

 effervescence ensues, and the beaker 

 may be overflowed if not closely 

 watched. The acids dissolve the 

 salts of lime and other substances 

 which may be in the material, and 

 the chlorate and bichromate of potash 

 combined with the acids destroy 

 the organic matter by oxidation. 

 After it has cooled, the material is 

 washed free of the acids and the 

 water drained off. It is then boiled 

 in sulphuric acid, using nearly the 

 same quantity as of the mixture of 

 muriatic and nitric acids. While 

 boiling, chlorate of potash, or the 

 bichromate of potash in fine powder, 

 is slowly added. If bichromate of 

 potash is used, a few drops of muria- 



tic is added. Generally the material 

 turns pretty white ; sometimes it will 

 not. As with muriatic and nitric 

 acids, a good deal of effervescence 

 ensues, and the same watchfulness is 

 necessary. Never add chlorate of 

 potash to cold sulphuric acid or there 

 will be explosion. It is safe to care- 

 fully add it in fine powder to boiling 

 sulphuric acid. I prefer chlorate of 

 potash in the whole process. I will 

 remark here in regard to the use of 

 the acids, that I have used them in 

 various ways. I have first boiled the 

 material respectively in sulphuric, 

 muriatic and nitric acids, and in com- 

 bination, and I have settled upon the 

 above process of first boiling it in a 

 mixture of muriatic and nitric acids, 

 and then in sulphuric acid ; I have 

 found this to answer with all material, 

 whether mud, lacustrine, sedimentary, 

 sub-plutonic, or fossil. 



After the boiling in sulphuric 

 acid, the material is transferred to a 

 wide-mouth bottle and repeatedly 

 washed. After the material is freed 

 of the acid, the light, broken portion 

 of the material will remain suspended 

 in the water above the settled portion. 

 This is drained off by means of the 

 rubber tubing, water is added, the 

 material is shaken, allowed to settle, 

 the floating matter drained off, and 

 this is repeated till nothing remains 

 but diatoms mixed with sand. If, 

 however, flocculent matter should re- 

 main, and this can be ascertained 

 with the microscope, it maybe broken 

 up and disposed of by means of com- 

 mon water of ammonia — concentrat- 

 ed water of ammonia one part, water 

 two parts, by measure — and further 

 washing. The ammonia should be 

 carefully used as there is danger of 

 injuring delicate forms by its use. 

 If, for instance, there be a quarter of 

 an inch depth of material in an eight- 

 ounce bottle, not more than half an 

 ounce, by measure, of the ammonia 

 should be used. The material is well 

 shaken in this for three or four min- 

 utes, the bottle then filled with water 

 and the washing continued till the 



