1) Collotype 2) Collotype printing 3) Copier 4) Duplicator 5) Hectograph 6) Photogelatin process 1) Hectograph 
• (n.) A picture obtained by the process of heliotypy.
He'li·o·type noun [ Helio- + -type .] A picture obtained by the process of heliotypy. 
Heliotype is a photographic process by which pictures can be printed in the same manner as lithographs, depending on the fact that a dried film of gelatine and bichromate of potash, when exposed to light, is afterwards insoluble in water, while the portion not so exposed swells when steeped. A mixture of gelatine, bichromate of potash, chrome alum,...