No, you've got it mixed up. 100 grams of sugar in enough water to make 1 liter total gives you a solution that is 10% sugar. This corresponds to 10 brix, which is ~1.040.

To figure out how many points it will add, you can divide 40 by the total volume you're adding it to and that will be close enough.

<edit>Sorry, I misread your post. 100 ml of syrup that weighs 359 grams . . . that's really dense. That's higher sugar content than honey, which should only be about 145 grams per 100 ml. Are you sure you measured right? That's more dense than sugar itself, with no water.

But to use honey as an example, 145 grams per 100 ml corresponds to a SG of 1.45. So each unit of honey adds 450 points of gravity. From there you take the final volume you'll have, the number of points you want, and calculate how much to add. For example, if you're adding it to 19 liters and want to add 1 liter of honey, that's 450 points divided by the total volume, so 450/20 = 22.5 points added.

It's important that your volume units be equal, that's why we can just say 450 points. If you want to add 100 mls of honey to 19 liters, that's 19.1 liters but the honey is in 100 ml increments, so divide it by how many 100 ml containers you could fill, which is 191. 450/191 = 2.35 points.

That might be a weird way of doing it, but it works. Well, close enough anyway, you need to know the actual SG of the sugar solution and a couple of minor things come into play (like SG points is not exactly the same as 4 * brix) but like I said, close enough.