Progress of Invention. 475 



PROGRESS OP INVENTION". 



A New Constant Battery. — The improved constant battery 

 of M. Blanc Pilipo is deserving of attention, being well adapted 

 for the purposes of telegraphy. It requires but one fluid, which may 

 be a mere solution of common salt. This battery may be con- 

 structed by placing the saline solution in a tolerably tall glass jar, 

 and adding to it powdered sulphur, so as to form a layer of 

 moderate thickness at the bottom. The positive metal consists of 

 a ring or cylinder of zinc, which is immersed in the fluid, but not 

 so as to come in contact with the sulphur ; and is suspended by a 

 wire, which passes up through a cork in the neck of the jar, and 

 forms the positive pole. The negative metal consists of a plate 

 of lead, or tin, which dips down into the layer of sulphur — 

 being slightly coated with sulphuret of copper, where it comes 

 in contact with the sulphur, and covered with an insulating 

 substance, when it approaches the zinc. A wire from this also 

 passes up through the cork, and forms the negative pole. 

 The mode of action of this battery is very simple. The 

 hydrogen which is evolved at the negative pole unites with some 

 of the sulphur — though the latter is insoluble, and a non-conductor 

 — and forms sulphuretted hydrogen, the sulphuret of copper 

 taking a part in the process which is indispensable, though it is not 

 as yet understood. When the sulphuretted hydrogen comes in 

 contact with the chloride of sodium, there results a double decom- 

 position, sulphuret of sodium and hydrochloric acid being formed. 

 The latter dissolves the zinc, and the resulting chloride of zinc is 

 changed into sulphuret, by the sulphuret of sodium, which again 

 becomes a chloride. During these changes, a small quantity of 

 sulphuretted hydrogen is evolved ; and this appears to be the only 

 objection to which this battery is liable. In other respects, it 

 possesses some important advantages ; it is very economical, both 

 as to the kind and amount of the substances required ; it 

 occupies but little space, and it continues in action a long time. 

 Other metals may be substituted for the zinc ; but in every case 

 the salt used in the solution must be incapable of decomposition by 

 sulphuretted hydrogen, or of precipitation by the metal which is 

 substituted. 



Purification by means of Electricity. — The fat obtained from 

 bones constitutes an important article of commerce ; it is, however, 

 obtained in a state of great impurity, and its purification is ex- 

 tremely difficult. The idea occurred to Dr. Dullo of using 

 electricity as a means of freeing it from the substances — chiefly 

 gelatine — which render even what is obtained from fresh bones 

 extremely nauseous, but which, fortunately, are decomposed by the 

 electric current, that, at the same time, exerts no action on the fat 

 itself. His process consists in gently heating the fat to about 40° 

 Cent., in a clean copper vessel, free from roughness in. the interior. 

 Sulphuric acid, diluted with ten times its volume of water, is added, 

 to an amount dependent on the degree of impurity which is to be 



