544 CONTRIBUTIONS TO BLOWPIPE ANALYSIS. 



baryta) remains dark blue, no precipitation of titanic acid taking 

 place. Strontia acts in the same manner, but a much larger quantity 

 is required to produce the reaction. 



7. DETECTION OF OXIDE OF MANGANESE WHEN PRE- 

 SENT IN MINUTE QUANTITY IN MINERAL BODIES. 



[First published in the Philosophical Magazine : February, 1852. ] 



It is usually stated in works on the Blowpipe, that the ' smallest 

 traces of maganese may be readily detected by fusion with carbonate 

 of soda, or with a mixture of carbonate of soda and nitrate of potash : 

 but this statement is to some extent erroneous In the presence 

 of much lime, magnesia, alumina, sesquioxide of iron, or other bodies, 

 insoluble, or of difficult solubility, in carbonate of soda, traces of oxide 

 of manganese may easily escape detection. By adding, however, a 

 small portion of borax or phosphor-salt to the carbonate of soda, these 

 bodies become dissolved, and the formation of a "turquoise enamel" 

 (manganate of soda) is readily effected. The process may be varied 

 by dissolving the test-substance first in borax or phosphor-salt, and 

 then treating the fused bead with carbonate of soda : the latter being, 

 of course, added in excess. By this treatment, without the addition 

 of nitrate of potash, the faintest traces of oxide of manganese in lime- 

 stone and other rocks, are at once made known. 



Note : — This method of examining bodies for the presence of man* 

 ganese, was recommended by Dr. Leop. S. Fischer \n 1861 (Leonh. 

 Jahrbuch: [18G1] 653), but the writer had forestalled him by nine 

 years, having already described it in 1852 — a fact apparently unknown 

 to the editor of the 4th edition of Plattner's Prohirkunst.* 



* This new edition of Plattner's treatise, although containing some valuable 

 additions from the pen of its editor, Dr, Theodor Richter, is not altogether free 

 from errors of omission. One of these, the writer may perhaps be allowed to 

 point out on personal grounds. In the third edition, p. 273, Plattner states 

 under the head of cryptolite — " Das Verhalten dieses seltenen Minerals vor dem 

 Lothrohre ist noch nicht ermittelt " In the new edition, JDr. Richter expands 

 this statement as follows : — " Kryptolit (Phosphocerit) — Das Lothrohrver 

 halten dieses seltenen Minerals, welches beim Aufldsen desgriinen and rothlichen 

 Apatits von Arendal, sowie des gerosteten Kobaltglanzes von Johannisberg in 

 Schweden, in Siiuren zuriickbleibt, ist noch nicht ermittelt." Now, the blow- 



