I have also wondering about the suggested 1 gram Gelatin per 250 ml colloidal silver, which seem to be just too much. But it depends on the concentration (ppm) of colloidal silver. I use that for 320 ppm gelatin capped colloidal silver, but will try with less next time.
Yes, scale the gelatin by the milligrams of silver, not ml of water. So for 20 ppm, you would want 1/16 th gram gelatin.
When I made up the formula, I calculated the amount of gelatin based on:
320 ppm particles
250 ml
14 nm diameter
10 % of the silver atoms on the surface of the particle.
1 molecule of gelatin for each surface atom.
The molecular weight of knox gelatin as 60,000 daltons. It may be heavier, that is the bottom of the range.
The atomic weight of silver is 107 daltons.
Given those parameters, the weight of the silver in the solution is 80 mg with 8 mg of surface atoms.
Gelatin is 600 times heavier than silver.
So, the amount needed to coat the particles with one gelatin molecule per silver surface atom would be then 4.8 grams.
But when I tried it out, that much gelatin made glop instead of liquid, so I kept reducing it until I got a stable solution that did not gel.
Apparently the gelatin molecules are so big that each one covers and protects more than one surface atom.
So while you think it is too much, I thought it was too little.