M, Yremy on the Fluorides, >^^^ I 5S' 



Boussingault communicates some experiments on the use of 

 arsenic in steeping grain for seed. This process has two objects, the 

 one to protect the harvest from disease, the other to prevent the 

 seed from being devoured by vermin. The substances generally- 

 used are salt, glauber salt, lime, and sulphate of copper. But 

 although these may hinder the development of cryptogamic 

 sporules, they have little effect in preventing the seed from being 

 eaten. The greatest part of the substance used remains in the 

 husk, which the animal rejects. 



The most effectual means is the employment of arsenic ; this 

 not only preserves the seed from decay, but if eaten by the 

 vermin it destroys them, being so strongly poisonous. By using 

 arsenic in a soluble form, such as the arsenite of soda, it may be 

 added to the grain in perfectly definite proportions. 



Boussingault^s process is as follows: — A solution of arsenite 

 of soda is prepared, which contains 57 grammes of arsenious 

 acid in the litre. Of this arsenical solution 3^ litres are taken and 

 added to 12| litres of w^ater. A hectolitre of corn is placed in 

 a large tub, and these L6 litres of mixture are added, the corn 

 being continually stirred. In about an hour the whole of the 

 liquid is absorbed, and the grain is then dried. It is, of course, 

 necessary to exercise extreme care in using the arsenical solution, 

 and it is well to colour it strongly by the addition of sulphate 

 of iron and prussiate of potash, so that its presence would be 

 readily betrayed. 



This steeping is not an unprofitable affair, for it first effectually 

 preserves the harvest, and secondly, by killing the vermin which 

 might devour it, converts them into useful manure. 



An important paper by Fremy on the fluorides is published 

 in the May Number of the same journal. The results he has 

 arrived at are best seen from his own summary of them. 



1. Hydrofluoric acid may be obtained anhydrous and pure, 

 by calcining in an apparatus of platinum hydrofluate of fluoride 

 of potassium previously well dried. In this state the acid is 

 gaseous at ordinary temperatures ; it attacks glass and all sili- 

 cious substances energetically, contrary to what has been asserted 

 on the subject in the last few years. 



2. All the experiments made, confirm the constitution of this 

 acid as admitted by most chemists, viz. that it is a hydrogen acid. 



3. The fluorides may be divided into three classes, each of 

 which is characterized by the possession of important properties. 

 The first class contains the anhydrous fluorides, and is analogous 

 to the chlorides ; the second class, the hydrated fluorides, which 

 comport themselves like the hydrochlorates ; in the third class 

 are found the hydrofluates of the fluorides, which are true acid 

 salts. 



