I have an old glass positive photo from about 1850. Does anyone know what process was used? Heliotipy? Puharotipy?

![helio](https://i.stack.imgur.com/sZNaW.jpg) 

I'm think that the author of the image is Puhar

I have an appointment with the Jozef Stefan Institute in Ljubljana, to analyze the material on the photo.

I look forward to your comments

Regards from Maribor/ Slovenia 
Bojan![enter image description here](https://i.stack.imgur.com/x3lCN.jpg)