PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 909 



by the author. The chart accompanying his paper contained the 

 wave lengths of 187 lines, Avith a probable error not exceeding 

 two-millionths of a millimeter. The lines being ruled by a divi- 

 ding engine upon a copper plate, are correct upon the chart to 

 about one-tenth of a millimeter. 



A New Chloride of Lead. 

 Prof. Nickles, of France, has formed a new compound called 

 perchloridc of lead, by exposing the chloride of lead to the action 

 of a current of chlorine in a solution of chloride of lime. The 

 perchloride thus obtained is a yellow liquid emitting a strong 

 smell of chlorine, and is a powerful agent for communicating that 

 element to other substances. It will dissolve gold, and produces, 

 with aniline and the analogous compounds, those beautiful colors 

 for which these substances are so remarkal)le. With morphine it 

 yields a color similar to that of the horizon at sunrise, and with 

 bucine a rich cherry-red. Now bucine and strychnine, both vege- 

 table bases extracted from nux vomica, are very diiEcult to dis- 

 tinguish from each other, and here perchloride of lead steps in 

 as a useful agent: for it so happens that it doQs'not produce red 

 with strychnine as it docs with bucine, and may therefore be nsed 

 to distinguish one substance from the other. It serves the same 

 purpose with regard to morphine antl the other alkaloids of opium. 

 Salts of lead and bismuth may also be distinguished by perchlo- 

 ride of lead, since it precipitates the former from their solutions, 

 and not the latter. It will carbonize cane-sugar and not glucose, 

 and blacken analine Avithout producing any eflcct either on fecula, 

 starch or dextrine. Like other perchlorides, it combines with 

 ether to form a very oaustie compound, which attacks both gold 

 and platinum, beside other metals. 



A Pest in Ciiigxoxs. 

 Mr. Lindermann, a German naturalist, has given in a medical 

 periodical published at St. Petersburg, Kussia, an account of a 

 newly discovered species of entozoa, found in large flocks, and 

 therefore called gregarine, from the Latin (/rex. It belongs to 

 the lowest class of animal organisms, and exists as a parasite in 

 human hair, forming numerous small dark-brown knots usually 

 at the ends of the hair. It is also found in other parts of the 

 body, and even in the blood, where it swims about imtil it grows 

 too large to enter the hair, and often becomes imbedded in the 



