3t4 EoUan Harp. — Chromate of Iron. 



a1fo evident from the manner in which the notes are generated ; for the aliquot parts of a 

 firing cor^tain in themfelves an infinite variety of difcords. Kircher in his Phonurg'ta, page 

 148, has attempted to account for thefe phenomena of the Eolian lyre, by fuppofmg the cur- 

 rent of air to ftrike on different portions of the firing. But this is abfolutely overturned 

 by experience : for, fuppofe the Eolian note to be one fifth above the original note of the 

 ftring, that is, one third of the whole; then, according to Kircher, the remaining part 

 would be at reft, which is falfe ; for an obftacle applied to any other point than the quiefcent 

 points of divifion, will deftroy the eolian tone. Befides, the chords that would arife on this 

 theory are not fuch as really take place in nature ; thus, where the chord confifts of the note 

 F and A, the firft: note F is produced, according to Kircher, by the blafts ftriking on one 

 fourth of the ftring : now, in this cafe, the remaining part of the ftring muft be at reft, ac- 

 cording to Kircher, but contrary to experience; or if it be agitated as one ftring, it muft 

 produce the note of three fourths of the whole ftring, that is a fourth above the bafs note; 

 whereas, the note really produced is the double octave to the third above the bafs note, as 

 may be feen in die table of the Folian tones. 



Analyfis of the Chromate of Iron of the Bafllde de la Carrade. By CiT. Tassaert.* 



HIS metallic combination which has been lately difcovered at the Baftide de la Carrade, 

 near Gaffin, in the department of Var, has the form of an irregular mafs ; its colour is a deep 

 brown, nearly refembling that of brown blende; it pofTeffes the metallic luftre ; its hardnefs 

 middling ; its fpecific gravity, 4,0326. Before the blow-pipe, it melts with difficulty ; and 

 when fufed with borax, it gives a dirty greenifh colour. 



This fubftance was fent to the Council of Mines, under the denomination of a brown 

 blende ; which it fufficiently refembles, though it is much heavier. In order to afcertain the 

 cffefl: of acids on this fubftance, two grammes were reduced into impalpable powder, and 

 boiled with weak nitrous acid. This acid not having attacked the powder, the muriatic 

 was tried, which being attended with no greater efFeil, it was thought proper to attack it by 

 a^calis. 



Two other grammes were therefore taken, and ignited with five times their weight of 

 pptafh. After a quarter of an hour's application of the fire, the crucible was fufFered to cool, 

 and the matter was mixed with water. The fluid exhibited a be&utiful lemon colour which 

 led to a fufpicion of the chromic acid; and, in fa6i, when trial was made with the nitates of 

 Icadjfilver, and mercury, there remained no further doubt of its prefence; p.irticularly when 



• Annales de Chimie, XXXI. no. I retain the vox^ Baftide, which is aa old provincial term, denoting 

 a country manfioo, or caftle. 



the 



