Ok, I'm going to tell you all the things I've been finding until now.
First of all, its website: http://www.ist-ag.ch/eh/ist-ag/en/home.nsf/contentview/42386E8CFD998086C12573C50027E83A
I talked with their engineers and they said me that we have to use address 0x78 (7 bit) plus one bit for read (1) or write (0).
I'm working with a waspmote from Libelium, and I'm using their libraries, but when I tried to use the 'requestFrom' or 'endTransmission' instructions the system halts.
Asking for this to the Libelium staff, they told me that i have to switch on the RTC (it uses the I2C bus too), but when I do that, my system halts too when it arrives to the 'RTC.begin' instruction.
Also I don't know how to read the humidity correctly.
After a lot of test, I have a code that seems to work sometimes.
uint8_t ADDRESS = B1111000; //0x78;
uint8_t ADDRESS_2 = B11110000; //0xF0;
uint8_t ADDRESS_3 = B11110001; //0xF1;
uint16_t MASK = B01111111;
uint8_t REG = 0x00;
if( !Wire.I2C_ON ) Wire.begin();
USB.println("\tHumidity & Temperature:\n");
// Wire.requestFrom(ADDRESS_3, quantity);
if (i==0 || i==2)
info = info & MASK;
humidity = (info << + info;
temperature = (info << + info;