THE TECHNOLOGIST. [Feb. 1, 1865. 



316 



IRON MINIUM. 



Iron Minium, a colouring matter founded on the iron principle, 

 is destined to supplant red lead and other pigments that have been used 

 until now for coating wood, iron, and other metals. The advantages of 

 iron minium are, its solidity, durability, cheapness, and, above all, its 

 property of preserving the iron completely from oxidation, and of hard- 

 ening the wood. These qualities, now acknowledged by first-rate manu- 

 facturers , have assured the fullest success to the iron minium, which is 

 advantageously employed all over Europe in the largest manufactories 

 and sugar works, as well as by the railway and steam navigation com- 

 panies. 



The great sblidity of this new paint is principally due to its extreme 

 purity. It contains no acid, no adulteration, and is therefore superior 

 to lead minium, which contains almost always large quantities of pow- 

 dered brick ; to the ochres, which are nothing but washed clay ; and to 

 colcothar, which by its very mode of production contains always some 

 sulphuric acid — a small quantity, it is true, but quite enough to attack 

 the iron and to eat into it, after a very short space of time. 



Iron miniuni forms a very smooth and stripeless coat upon the iron, 

 varnishing, as it were, the metal, and preventing the atmospheric in- 

 fluences from having any action upon the paint. 



It results, from statements made by eminent English and French 

 chemists and engineers, that the use of red lead, and generally of all 

 preparations in which lead is employed, is injurious to the iron coated 

 with it. Thej T examined vessels in which the iron, after one single voyage 

 to the East Indies, was visibly corroded, and blisters discovered on the 

 coating itself, containing a clear liquid, and exposing thus the iron, 

 which presented a certain number of metallic crystals. Each blister 

 was found to be a sort of galvanic battery, and corrosion in such a case 

 is unavoidable, because there is always a chemical action going on, when- 

 ever electricity is produced. This phenomenon must needs continue, as 

 long as there remains any red lead, in consequence of the immediate con- 

 tact of the lead paint with the metallic surface. Red lead, therefore, as 

 well as any other lead pigment, ought to be completely excluded from 

 the paint of iron vessels. 



The best result, therefore, has been obtained by coating with iron 

 minium the exterior and the interior of iron vessels. 



Iron minium has been tried by first-rate manufacturers, and always 

 to their greatest satisfaction ; it is employed in the most important 

 building yards ; for sugar works; for railways and steam navigation ; 

 for the prisons of Belgium and other countries ; it has been adopted by 

 the great public services, civil and military, in almost all the countries 

 of Europe. 



Iron minium is also prefeixed for the under coat of all -the running 



