>Jenny_Morris?= <[log in to unmask]> posted:
>I need a scientific mind (Julia Barrett, where are you?) to help me answer
>a question posed by the husband of a client.  This lovely couple have just
>become parents for the first time.  Both are in their mid-40's and he is a
>chemist.  Baby delivered at 37 wks via c-sect weighing just 3 and a half
>pounds, due to a large fibroid that was impairing baby's growth.  Mom
>initiated pumping and is producing great milk volume, and baby is even
>nursing very well.  Left the NICU at 10days old, no monitors at all.  So
>what's the problem??
>      They rented a gram scale and are checking several times per day.  Her
>gain is great, about an ounce per day.  Dad is concerned that the amount
>of intake in grams does not equal the amount of weight the baby gains.  He
>says that cc's and ml's are liquid measurements, and grams are mass
>measurements.  Thankfully, this baby is doing very well, but I'm a bit
>confused by his concern.  Can any of you enlighten me, not so much to
>explain to him, but to understand the question myself!

I am at my desk, drinking coffee and preparing to copyedit a crop science 
paper. On a Sunday morning!

There's a nifty conversion for calculating the mass of a liquid from its 
volume: multiply the number of milliliters of a substance by its specific 
gravity to get the weight in grams. That's handy if one wants to avoid 
having to weigh an empty container and subtract its weight from the total. 
In the baby's case, however, it's easy to obtain the mass of the milk---the 
baby is the container:

post-feed weight of container = pre-feed weight of container + whatever 
container has consumed

Liquids have mass, they can be weighed. (My random thought here is that 
dairy cow milk production in the USA is measured by weight not volume; the 
official hundredweight measure = 100 pounds = approx. 8 gallons).

I hope I understood the dad's question correctly. I'm perplexed too. I'm 
certain he knows liquids have mass. I suspect he's trying to bring some 
nice, soothing scientific order to a stressful situation. (I sympathize 
with the inclination, so much so that it occurs to me that if they have a 
super-precise scale and they know the volume of milk going into the baby, 
they could back-calculate the specific gravity of the mother's milk and 
track how that changes over time. Oh my. Probably best not to suggest that! 
;-) )

regards,
Julia

Julia R. Barrett
Freelance Science Writer & Editor
Mom to Sean (6) and Kira (2)
Madison, Wisconsin

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